PROC. BIOL. SOC. WASH. 103(2), 1990, pp. 279-299 A NEW PYRGULOPSIS (GASTROPODA: HYDROBIIDAE) FROM SOUTHEASTERN CALIFORNIA, WITH A MODEL FOR HISTORICAL DEVELOPMENT OF THE DEATH VALLEY HYDROGRAPHIC SYSTEM Robert Hershler and William L. Pratt Abstract.?Pyrgulopsis giulianii, new species, from a few, mid-elevation streams in southern Sierra Nevada (Indian Wells and Kern River Valleys), is described and new records for three other local congeners also are given. Details of shell form and penial morphology distinguish the new snail from related forms found in Owens Valley. Zoogeographic patterns of Death Valley System Pyrgulopsis support the hypothesis that a highly integrated pluvial drainage was present in the region, and also suggest that the system had various historic connections (possibly non-contemporaneous with the above) to adjacent areas. A model of drainage evolution of the Death Valley System is presented, based on distributional data of hydrobiids and other organisms of perennial waters. This is the third and final paper in a series on systematics of springsnails (Gastropoda: Hydrobiidae) from Death Valley System, southeastern California and southwestern Nevada. Earlier contributions dealt with fauna from the Ash Meadows spring oasis in Amargosa Desert (Hershler & Sada 1987), and Owens and Amargosa Basins (exclusive of above, Hershler 1989). Results of survey of remaining portions of the system and ad- jacent areas are summarized herein, includ- ing description of a new Pyrgulopsis and new records for three other congeners. A model for historical development of drain- age in the Death Valley System is presented, largely based on zoogeography of resident Pyrgulopsis. Materials and Methods Localities visited during this portion of the survey are listed in Appendix 1, and consisted of low- to mid-elevation springs and perennial streams. Fuller treatments of taxa (other than the new species) are in Hershler (1989) and Hershler & Sada (1987). Shell morphometric methodology is that of Hershler (1989). Dots on distribution maps represent one or several closely spaced lo- calities. Repositories of material examined are indicated in the text as follows: LACM? Los Angeles County Museum of Natural History; SBMNH?Santa Barbara Museum of Natural History; UNLVM?University of Nevada at Las Vegas Museum of Natural History; USNM ?National Museum of Natural History; WBM?Walter Miller per- sonal collection. Systematics Family Hydrobiidae Troschel, 1857 Genus Pyrgulopsis Call & Pilsbry, 1886 Pyrgulopsis giulianii, new species Southern Sierra Nevada springsnail Figs. 1-4 Pyrgulopsis cf. stearnsiana. ?Hershler, 1989:194 (Sage, Sand Canyons; figs. 37- 40). Material examined. ?California. Kern County: Stream in Sage Canyon, USNM 853520, 857975; Stream in Sand Canyon, USNM 860444 (holotype), 853519 (para- 280 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Table 1. Shell parameters for Pyrgulopsis giulianii. UNSM catalog number and number of specimens (in parentheses) are given beneath locality name. WH = number of whorls, SH = shell height, SW = shell width, LEW = length of body whorl, WBW = width of body whorl, AL = aperture length, AW = aperture width, W = whorl expansion rate, D = distance of generating curve from coiling axis, T = translation rate, SA = aperture shape. Locality Parameter Sand Canyon 853519(10) Sage Canyon 853520(15) Ninemile Canyon 860446(6) Cow Canyon 860448 (8) WH mean 4.13 4.15 4.25 4.44 SD 0.13 0.16 0.27 0.18 range 4.00-4.25 4.00-4.50 4.00-4.50 4.00-4.50 SH 2.43 (mm) 2.58 3.33 3.16 0.19 0.14 0.41 0.15 2.06-2.74 2.39-2.87 2.82-3.99 3.01-3.48 SW 1.68 1.67 2.26 2.17 0.11 0.13 0.25 0.12 1.45-1.81 1.52-2.04 2.26-2.60 1.98-2.37 LBW 1.90 1.99 2.55 2.38 0.16 0.11 0.23 0.10 1.61-2.13 1.83-2.22 2.27-2.78 2.24-2.49 WBW 1.43 1.48 1.82 1.77 0.08 0.08 0.18 0.08 1.27-1.53 1.37-1.61 1.56-2.08 1.65-1.89 AL 1.21 1.18 1.59 1.55 0.11 0.08 0.13 0.07 1.03-1.36 1.06-1.39 1.41-1.76 1.35-1.55 AW 0.97 0.96 1.31 1.21 0.07 0.05 0.13 0.06 0.88-1.06 0.88-1.13 1.16-1.49 1.08-1.26 W 1.95 1.99 1.88 1.65 0.15 0.24 0.18 0.19 1.69-2.23 1.59-1.89 1.61-2.14 1.45-2.03 D 0.60 0.62 0.58 0.56 0.04 0.06 0.04 0.03 0.54-0.68 0.51-0.74 0.50-0.62 0.51-0.61 T 4.90 6.29 4.84 4.65 0.47 0.47 0.91 0.51 4.27-5.65 4.32-8.61 3.84-5.96 4.04-5.31 SA 1.25 1.23 1.22 1.21 0.06 0.06 0.04 0.06 1.14-1.36 1.13-1.34 1.19-1.29 1.15-1.30 types), 857974, SBMNH 35140 (paratypes); Stream in Sand Canyon, 3.7 km up canyon from US 6, WBM 4230, 4387; Small streamlet, S Fork Short Canyon, USNM 860445; Stream in Ninemile Canyon, USNM 860446; Stream in Grapevine Can- yon, USNM 860447; Stream in Grapevine Canyon, 7.2 km up canyon from US 6, WBM 4229,4360; Stream in Cow Canyon, USNM 860448. Diagnosis.? A small- to moderate-sized species with ovate conic shell. Penis small relative to head/foot; penial lobe reduced, filament elongate relative to remaining pe- nis. Penial glandular ridges 1?4; ventral ridge sometimes borne on low swelling. VOLUME 103, NUMBER 2 281 Fig. 1. Scanning electron micrographs of shells of Pyrgulopsis giulianii, new species: a, b, USNM 860444, holotype (standard and side views); c, USNM 860447; d, USNM 860446; e, USNM 860448; f, USNM 860445. The holotype is 2.75 mm tall (other micrographs are printed at the same scale). Description.? Shell morphometric data are in Table 1. Shell (Fig. 1) 2.0-4.0 mm high, height/width, 130-170%. Apex pro- truding (Fig. 2e). Whorls, 4.0^.5, slightly to moderately convex, with indented su- tures and slight sub-sutural shoulders. Ap- erture ovate, angled above, about half as tall as body whorl. Inner lip straighter than out- er, slightly to moderately thickened and re- flected, adnate to small portion of or slightly separated from body whorl. Outer lip thin; apertural plane slightly tilted relative to coiling axis. Umbilicus slit-like to moder- ately open. Shell surface usually encrusted with brown-black deposits. Operculum (Fig. 21) paucispiral, with ec- centric nucleus; whorls, 3-4. Opercular sur- face attached to foot bearing elongate (ca. 282 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 2. Pyrgulopsis giulianii: a-d, Radula, USNM 860448 (a, Centrals,bar = 12.0 fim; b, Laterals and inner marginals, bar = 8.6 Mm; c, Inner marginal, bar = 7.5 fim; d, Outer marginals, bar = 8.6 /am); e, Shell apex (bar = 136 iiva), USNM 860447; f, Dorsal view of operculum showing thickened callus (bar = 1.0 mm), USNM 853519. VOLUME 103, NUMBER 2 283 - s. WL '*? *-V?MS gB ?? "..V * - X?* y. , ."* Fig. 3. Penes (whole mounts) of P. giulianii: a-c, Dorsal aspects; d, e, Ventral (a, e, USNM 857974, bar = 0.25 mm [others to scale]; b-d, WBM 4229). Note stained glandular ridges (both dorsal and ventral examples visible) and black subepithelial pigment (mostly in penial filaments). 50% of operculum length), gently curved, thickened, non-calcareous, amber callus (similar to those described for congeners by Taylor 1987). Dark, grey-black epithelial pigment on most of snout (except distal tip), proximal portion of cephalic tentacles, along anterior and posterior edges of sides of head/ foot, and part or all of operculigerous lobe. Pigment on central portions of sides of neck absent to dark (dense subepithelial pigment cluster present in area). Ctenidial filaments, ca. 20. Osphradium ca. 25% of ctenidium length. Style sac and remaining stomach ca. equal in length. Small caecal chamber present. Radular (Fig. 2a- d) formula: 5(6)-1-5(6), 2(3,4)-1-3(4,5), 23- 29, 23-35 (from two populations). Central tooth broadly trapezoidal; basal cusps short, triangular; basal process moderately exca- vated. Penis (Fig. 3) rarely protruding be- yond edge of mantle collar, usually of stunt- ed appearance, relatively fiat (apart from ventral swelling), longer than wide. Fila- ment slender, sub-equal to remaining penis length. Reduced lobe short relative to fila- ment length. Tip of lobe usually ornament- ed with small glandular ridge; somewhat larger, single ridges on dorsal penial surface 284 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 50 100 150 I I I Kilometers Fig. 4. Distribution of P. giulianii. at central position ca. halfway between base of penis and base of filament, on ventral surface near (sometimes on) inner edge. A single specimen (from Cow Canyon) had a small fourth ridge located on dorsal surface between ridge on lobe and central dorsal ridge. Filament with dark sub-epithelial pig- ment streak; pigment granules also scattered throughout small area surrounding base of filament. Albumen gland sub-equal to cap- sule gland. Seminal receptacle small, posi- tioned anterior to bursa copulatrix. Bursa copulatrix small relative to capsule gland, positioned partly posterior to gland. Type locality. ?A moderate-sized stream in floor of Sand Canyon, Kern County (cen- ter of section 7, T 25S, R 38E; ca. 1068 m elevation) (Hershler 1989:fig. 8d). Snails common in shallow water (<0.5 m), on wa- tercress. Distribution and habitat.? Known from six small- to moderate-sized streams in VOLUME 103, NUMBER 2 285 southern Sierra Nevada, of which five are in western Indian Wells Valley and one is in adjacent Kern River Valley (Fig. 4). Etymology.? Named after Derham Giu- liani, an avid student and indefatiguable collector of Great Basin biota, who discov- ered a number of new localities of Pyrgu- lopsis in Owens Valley area. Remarks. ? Hershler (1989) tentatively assigned this snail to P. stearnsiana (Pilsbry) based on similarity of shell, but later com- parison with near-topotypical, preserved material of the latter revealed striking dif- ferences in their penes and indicated sepa- rate species status for the populations in southern Sierra Nevada. Pyrgulopsis giuli- anii is distinguished from close allies found in Owens Valley (to the north) by its com- bination of large size, moderately elongate shell, and small penis with small lobe and very reduced ventral swelling. Pyrgulopsis micrococcus (Pilsbry, 1893) Fig. 5 Amnicola micrococcus Pilsbry in Stearns, 1893:277 (Small spring in Oasis Valley, Nevada; fig. 1). Pyrgulopsis micrococcus. ?Hershler & Sada, 1987:788 (numerous localities, mostly in Ash Meadows; figs. 8a, 9-16). Pyrgulopsis micrococcus.? Hershler, 1989: 182 (numerous localities; figs. 17c, d, 20- 25). Paludestrina stearnsiana.?Berry, 1909:78 (Rill near mouth of Mill Creek Canyon). Amnicola stearnsiana. ?Berry, 1948:59 (Mill Creek Canyon). Paludestrina longinqua. ? Hannibal, 1912: 34 (Spring branch, mouth of Mill Canon, fide Berry 1909). Hydrobia sp.-Taylor, 1954:69 (Old Wom- an Springs, Inyo Co.). Material examined. ?California. San Bernardino County: Mohave River at Bar- stow, USNM 713484; Old Woman Springs, 20.8 km SE of Lucerne Valley, LACM 106639, 107741; USNM 526395; Cushen- bury Springs, 16 km SE of Lucerne Valley, LACM 106640, 106660, 106661, WBM 4270, USNM 860449; Box S Spring, 2.6 km SE of Lucerne Valley, LACM 106641; Box Spring (probably same as above), WBM 4266; Broadbent Spring, 10.2 km ESE of Lucerne Valley, LACM 106639, WBM 4264; Bear Lake, USNM 175096; Roadside spring between N shore highway and Big Bear Lake at point 1.2 km E of road which crosses lake, WBM 4274; Spring-fed pond between N shore road and Big Bear Lake, at point 1.6 km W of road which crosses lake, WBM 4276; Spring zone SW of Big Bear Ranger Station, USNM 860450; Spring, S side of CA Highway 18, N side Big Bear Lake, LACM 106644; Rill near mouth of Mill Creek Canyon, LACM 106646, 106647; Small stream, Mill Creek Canyon, SE of CA Highway 38, 0.34 km NE of Power House Canyon Bridge, LACM 106645; Mill Creek at Thurman Flats Picnic Area, USNM 860451; Spring 4.5 km up Mill Creek Rd. from junction with Yucaipa Rd., WBM 4263. Nevada. Clark County: Cold Creek, UNLVM 3212; Willow Creek, UNLVM 3451. Diagnosis.?A small-sized species, with globose to ovate-conic shell. Penis with moderate-sized lobe; distal edge of lobe usu- ally ornamented with small glandular ridge. Remarks. ?This snail is very similar, even in general form of penis and disposition of glandular ridge, to P. stearnsiana (Pilsbry), which occurs in Central California, "from Sonoma County to Monterey County along the coast and inland in the foothills of the Sierra Nevada" (Taylor 1981:152). The sole reliable distinguishing feature appears to be the larger and longer penial lobe of P. mi- crococcus, but study of additional material of P. stearnsiana will be necessary to deter- mine generality of this difference. Populations in San Bernardino Moun- tains are separated from remaining range of P. micrococcus to the north by poorly watered (and apparently snailless) Mohave Desert (but note that an old collection was 286 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON taken from an intermediate locale at Bar- stow). Populations in the headwaters of the Willow Creek drainage (which enters Indian Springs Valley) on the northeast slope of Spring Range are apparently relicts from pre- Wisconsin time, since the snail is absent from well-studied (26 samples) late Wis- consin sediments from the valley floor at the mouth of Willow Creek (Quade & Pratt 1989). Pyrgulopsis owensensis Hershler, 1989 Fig. 6 "Undescribed form of Fontelicella,'(c!).? Taylor 1985:318 (Owens Valley, E Fork Walker River; unfigd.). Pyrgulopsis owensensis Hershler, 1989:187 (numerous localities in eastern Owens Valley; figs. 26a-d, 27-32). Material examined.? California. Mono County: Spring, W side East Fork Walker River, USNM 860452.-Nevada. Lyon County: Spring at Wiley Ranch, USNM 860453. Diagnosis.?A small- to moderate-sized species with globose to ovate-conic shell. Penis large relative to head/foot; lobe en- larged, filament short. Penial glandular ridges, 2-6; ventral ridge borne on pro- nounced swelling. Remarks.? Populations in Walker Basin represent significant range extension of species (previously known only from Owens Valley) into pluvial Lahontan System. Pyrgulopsis wongi Hershler, 1989 Fig. 7 Pyrgulopsis wongi Hershler, 1989:196 (nu- merous localities in Owens Valley area; figs. 41-47). Material examined.? California. Mono County: Springs SW of Conway Summit, USNM 860454; Spring, Pizona, USNM 869034; Upper Pizona Spring, USNM 869035; Spring in West Queen Canyon, USNM 860511; Truman Spring, USNM 860512. Inyo County: Spring NW corner of Round Valley, USNM 860455; Spring, SW corner of Round Valley, USNM 860456; "Smoke Spring," USNM 853926; Springs, Marble Canyon, USNM 860457 (upper spring), 860458 (lower); Spring, 1.2 km NW of Big Pine Spring, USNM 860459; Spring at McMurry Meadows, USNM 860513; Spring on N side of Red Mountain, USNM 860514; Spring in canyon N of McGann Springs, USNM 860515; McGann Springs, USNM 869036; Tub Springs, USNM 869037; Spring, 0.1 km N of Independence Creek, USNM 860460; Springs SW of Lone Pine, USNM 869038 (North), USNM 869039 (South); Spring at Lower Diaz Creek, USNM 869040; Springs at Upper Diaz Creek, USNM 869041 (North), USNM 869042 (South); Spring S of Carrol Creek, USNM 869043; Stream, Talus Canyon, USNM 860461; Canyon N of Johnson Can- yon, USNM 853925; Johnson Canyon, USNM 853928; Stream, Tunawee Canyon, USNM 860462; Canyon S of Tunawee Can- yon, USNM 853927; Stream, Sacatar Can- yon, USNM 860463 (N Fork), USNM 860464 (S Fork). Nevada. Esmeralda Coun- ty: Springs at Dyer Ranch, USNM 860465. Mineral County: Huntoon Spring, USNM 869033. Diagnosis.?A. small- to moderate-sized species with globose to low conical shell. Penis elongate and broad relative to head/ foot; filament large and lobe moderate-sized. Glandular ridges, 7-12, of which two are borne on prominent ventral swellings lo- cated near distal edge of lobe. Remarks. ? The Inyo County popula- tions fall into previously known range of species. Localities in Fish Lake Valley and Mono Valley represent significant range ex- tensions. The latter area, with a recent his- tory of significant volcanic activity (Gilbert et al. 1968, Kilbourne et al. 1980), previ- ously had been considered devoid of peren- nial water mollusks (Taylor 1985:318). VOLUME 103, NUMBER 2 287 0 L 50 100 150 _J I I Kilometers Fig. 5. Distribution of P. micrococcus (Pilsbry). Discussion In an earlier paper, Hershler (1989) con- cluded that springsnail zoogeography (in part) supports the frequently advocated hy- pothesis that a highly integrated pluvial drainage was present in Death Valley Sys- tem (Fig. 8) during late Quaternary, pluvial period (10,000-100,000 B.P.). These data also provide evidence of historic connec- tions between the system and adjacent re- gions, some of which were probably pre- Quaternary. Results of this study support this conclusion insofar as additional ex- amples of both of the above features have been discovered, which are synthesized with the earlier data below. Pyrgulopsis is the most diverse (13 spp.) and among the most widespread genera of 288 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 6. Distribution of P. owensensis Hershler. freshwater mollusks in the Death Valley System, and therefore is a highly suitable subject for zoogeographic inquiry. Other prosobranchs associated with perennial waters, Tryonia Stimpson, 1865 (Hydro- biidae), and Assiminea Fleming, 1828 (As- simineidae), are less diverse and consider- ably more localized in the system (Taylor 1985, Hershler 1987, Hershler & Sada 1987, Hershler 1989), and largely are excluded from further discussion. Distributions of Death Valley System Pyrgulopsis are summarized in Table 2. For purposes of discussion, it is assumed that non-aquatic dispersal of these snails is in- significant, on a large scale, and that distri- bution of a species reflects past or present continuity or near-continuity of aquatic habitat. Evidence for pluvial integration of Death VOLUME 103, NUMBER 2 289 0 L 100 150 I I Kilometers Fig. 7. Distribution of P. wongi Hershler. Valley System is provided by distributions of two of the more widespread forms. The range of Pyrgulopsis wongi (Fig. 7) closely approximates pluvial Owens River drain- age, as this snail extends from Mono Valley through both Adobe and Long Valleys into Owens Valley. This supports inclusion of the former valley (currently without surh- cial water connection to Owens Basin and considered of uncertain historic relation- ships by Hubbs & Miller 1948:79) in pluvial Owens River drainage. Distribution of P. micrococcus (Fig. 5) similarly supports in- tegration of now-isolated sub-units of plu- vial Amargosa River drainage (i.e., sites along modern course of river, Ash Mead- ows, northern Death Valley). This species also has been found (Quade & Pratt, pers. comm.) in Wisconsin pluvial sediments of Chicago Valley, a now dry tributary of the 290 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 8. Pleistocene Death Valley System showing drainage relations (not necessarily contemporaneous). Stippled areas encircled by dashed lines may not have contained lakes for significant portions of the pluvial period. VOLUME 103, NUMBER 2 291 Amargosa Basin, together with two other snails from Amargosa drainage, Tryonia variegata Hershler and Sada and an unde- scribed Assiminea species now living at Ash Meadows and elsewhere in the drainage. In addition, presence of P. micrococcus in Pan- amint Valley and San Bernardino Moun- tains more generally supports pluvial inte- gration of the three rivers comprising Death Valley System (Owens, Amargosa, Mo- have). Snail distributions also imply the follow- ing historic drainage connections: a) be- tween Owens Basin and both Lahontan Sys- tem, and Deep Springs and Fish Lake Valleys; b) between lower Owens Basin and adjacent Kern River Valley; c) between Mo- have and Los Angeles Basins; d) between Amargosa Basin and both Frenchman Flat and Indian Springs Valley; and e) between the system and Saline Valley. Implied connections between Amargosa Basin and both Frenchman Flat and Indian Springs Valley (which do not currently drain into the system) are intriguing because these areas are currently separated by low, pre- sumably labile divides of alluvial material and could have drained to the Amargosa possibly during the Quaternary ("alluvial cone [drainage] connection" of Hubbs & Miller 1948:147). However, other examples are clearly untenable within the framework of modern regional topography and prob- ably reflect Neogene conditions. For in- stance, distribution of P. wongi implies for- mer aquatic connections between Owens Basin and Deep Springs and Fish Lake Val- leys to the east. These areas are profoundly separated by White Mountains, and surfi- cial water connections between them during pluvial period is extremely unlikely. (The latter two valleys drained [if at all] into La- hontan System [Miller 1928, Hubbs & Mil- ler 1948].) Note, however, that inception of Basin and Range was a relatively recent event (ca. 2-6 million years B.P.) in Owens Valley area (Bachman 1979, Giovannetti 1979, St. Amand-Roquemore 1979) and Table 2. Distributions of Pyrgulopsis spp. Basins or valleys considered part of the Death Valley System by Hubbs & Miller (1948:table 1) are indicated by asterisks. Species Distribution P. aardahli P. amargosae P. crystalis P. erythropoma P. fairbanksensis P. giulianii P. isolatus P. micrococcus P. nana P. owensensis P. perturbata P. pisteri P. wongi Northern Owens Valley* Lower Amargosa Basin* Ash Meadows (Amargosa Ba- sin)* Ash Meadows (Amargosa Ba- sin)* Ash Meadows (Amargosa Ba- sin)* Indian Wells Valley,* Kern River Valley Ash Meadows (Amargosa Ba- sin)* Frenchman Flat, Indian Springs Valley, Amargosa Basin,* Northern Death Val- ley,* Panamint Valley,* Sa- line Valley, San Bernardino Mtns. (Mohave,* Los Ange- les Basins) Ash Meadows (Amargosa Ba- sin)* Owens Valley,* E Fork Walker Basin Northern Owens Valley* Ash Meadows (Amargosa Ba- sin)* Mono Valley,* Long Valley,* Adobe Valley,* Owens Val- ley,* Huntoon Valley, Deep Springs Valley, Fish Lake Valley distribution of P. wongi could reflect prior drainage relationships. A second example involves P. micrococcus, whose distribution suggests a former aquatic connection be- tween Saline Valley and pluvial Owens drainage. Saline Valley is a small, but deeply down thrown basin that probably was closed to external drainage during pluvial times (Hubbs & Miller 1948). The valley is sep- arated from Panamint Valley (which was part of the pluvial Owens System) by the Nelson Range, which connects the Inyo and Cottonwood Ranges. However, Grapevine Canyon, at the eastern end of the Nelson 292 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Range, is the trace of a predominantly slip- strike fault (Cemen et al. 1985:fig. 1), and restoring 10 km of movement along this fault would open Saline Valley to Panamint Valley drainage. Taxonomic affinities of Death Valley Sys- tem Pyrgulopsis can only be addressed in a general sense owing to relative paucity of data on adjacent extra-limital faunas, but are consistent with the above in that they point toward a diverse origin of resident forms. Pyrgulopsis wongi from western portion of system (and Lahontan System) is not closely related to other local forms, but is very sim- ilar to P. californiensis (Gregg & Taylor), from west and south of the system (Taylor 1981:152). Also present in Owens Basin is an apparent species flock, comprising P. ow- ensensis and three local endemics, without obvious affinities to other snails found in the system. The presence of P. owensensis in Lahontan System suggests possible der- ivation of the Owens Basin group from the north via Neogene Owens River. Note that P. nevadensis (Stearns), from Lahontan Sys- tem, has a pattern of penial glandular ridges (discerned in rehydrated material; Hershler & Thompson 1987) suggesting a close re- lationship with this group. Pyrgulopsis mi- crococcus has affinities with P. amargosae Hershler from lower Amargosa Basin, but is much more similar to P. stearnsiana from west of the system. Ash Meadows endemics include (at least) two species flocks com- posed of pairs of very similar forms: a) P. erythropoma (Pilsbry) and P. crystalis Hershler & Sada, having trochoid shells and unlobed penes bearing single, central ven- tral glandular ridge; and b) P. nanus Hersh- ler & Sada and P. isolatus Hershler & Sada, having globose-conic shells and large-lobed penes bearing single glandular ridge at ter- minus of lobe. Inclusion of P. pisteri in the former group and P.fairbanksensis Hershler & Sada in the latter is conjectured on basis of general penial similarity, but these dis- play other significant morphological differ- ences from respective group members and may represent additional lineages. Ash Meadows snails are dissimilar to an unde- scribed form of the nearby Las Vegas and Pahrump Valleys, which is closely related to P. deserta (Pilsbry) from Virgin Basin; and preliminary observations suggest that the fauna, except P. micrococcus, instead was derived from that of White River drain- age. For example, P. fairbanksensis is sim- ilar to undescribed taxa from Pahranagat, White River, and Railroad Valleys in south- eastern Nevada, whereas both P. nana and P. isolatus closely resemble P. avernalis (Pilsbry) of Moapa warm springs complex (also in southeast Nevada). A hypothetical model of the history of Death Valley System and adjacent drain- ages is described below, based on both geo- logical evidence and distributions of springsnails and other fauna of perennial waters. The model, which partly conforms to interpretations advanced by Hubbs & Miller (1948), Taylor (1985), and Minckley et al. (1986), is heuristic in intention, and presented as a framework for testing hy- potheses generated from study of zoogeog- raphy of regional aquatic organisms. In early Miocene time (Fig. 9), the Mo- have River region probably drained to the Pacific, in the Los Angeles Basin area, as did most of the region immediately east of the present Sierra Nevada.1 Fauna in these drainages included progenitors of the pres- ent Pacific coastal Pyrgulopsis and snails in Mohave System which gave rise to P. mi- crococcus. The White-Virgin River region, 1 Occurrence of P. micrococcus in San Bernardino Mountains, Los Angeles Basin, suggests former drain- age of the Mohave through this area. Three other fresh- water mollusks (Anodonta californiensis Lea, Pisidium compressum Prime, Valvata humeralis Say) also occur (or occurred until recently) in both Los Angeles Basin and Death Valley System and not in coastal California immediately to the north (Taylor 1981, 1985). Addi- tionally, one of the three primary freshwater fishes of Los Angeles Basin, Pantosteus santaanae (Snyder), may have originated within the ancestral Colorado River drainage (Smith 1966, Minckley et al. 1986). VOLUME 103, NUMBER 2 293 Fig. 9. Death Valley System and adjacent drainages during early Miocene, > 16 Ma, before the develop- ment of basin and range structure. Screened areas are Pacific Ocean. Drainage lines are diagrammatic. It is doubtful whether any drainage, possibly excepting the San Joaquin on west slope of Sierra Nevada (Huber 1981) even approximately followed its modern course at this time. 1 = Future area of Death Valley; 2 = Future area of Owens drainage; 3 = Discharge of Ow- ens-Kern drainage to Pacific; 4 = Ancestral Mohave River; 5 = Los Angeles Basin area; 6 = Amargosa River (included for convenience, existence in early Miocene uncertain); 7 = Ash Meadows; 8 = White-Virgin River system; 9 = Pahrump Valley (present location, which dates from late Miocene); 10 = Ancestral San Joaquin River. including the ancestral Amargosa and Col- orado Rivers, drained eastward across northern Arizona and southeastern Utah to the Gulf of Mexico (Nilsen & McKee 1979), and was then inhabited by progenitors of the present Moapa River and Ash Meadows species complexes. Shift to an extensional tectonic regime and uplift of the basin ranges in the late Miocene (Dickinson 1979) produced major alter- ations in drainage relations (Fig. 10). Uplift of the Spring, Sheep, Las Vegas, Pahranagat, and associated minor ranges, severed the Amargosa Basin; transferring its drainage to the Death Valley System and introducing progenitors of the Ash Meadows Pyrgulop- Fig. 10. Death Valley System and adjacent drain- ages during later Miocene, < 15 Ma, after development of basin and range structure in southern Nevada. 1 = Death Valley region; 2 = Owens drainage region; 3 = Discharge of Owens-Kern drainage to Pacific; 4 = An- cestral Mohave River; 5 = Los Angeles Basin area; 6 = Amargosa River (see note in Fig. 9); 7 = Ash Mead- ows; 8 = White-Virgin River system; 9 = Pahrump Valley (see note in Fig. 9); 10 = Ancestral San Joaquin River; 11 ?= Bouse Embayment; 12 = "Lake Huala- pai." sis to the system.2 Pyrgulopsis micrococcus penetrated upstream into the Amargosa drainage and presumably gave rise to the local P. amargosae. Direction of flow of Colorado River was reversed, with the river coursing westward in approximately its modern path. Ponding in the present Lake Mead-Lake Mohave area produced the Hu- alapai limestones. These have been inter- preted as marine (Blair & Armstrong 1979), but Taylor (1983) showed that the late Mio- cene molluscan fauna, as far downstream as Parker Dam, consisted of typically fresh- water species (and not the marine taxa char- acteristic of the Bouse Embayment). Ac- cordingly, we map the area of the Hualapai 2 Progenitors of the endemic goodeid fish Empetrkh- thys (sister group to Crenichthys of White River drain- age; Parent! 1981) also may have been introduced by this event. 294 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 11. Death Valley System and adjacent drain- ages during middle Pliocene, ca. 5 Ma, after initiation of major tilting of Sierra Nevada block fault. 1 = Death Valley region; 2 = Owens River; 3 = South Fork Kern River; 4 = Ancestral Mohave River; 5 = Los Angeles Basin area; 6 = Amargosa River; 7 = Ash Meadows; 8 = White-Virgin River system; 9 = Pahrump Valley; 10 = Ancestral San Joaquin River; 11 = Bouse Em- bayment. Fig. 12. Death Valley System and adjacent drain- ages during late Pliocene, ca. 4 Ma, after uplift of Trans- verse Ranges and before formation of Death Valley graben. 1 = Death Valley region; 2 = Owens River; 3 = South Fork Kern River; 4 = Mohave River; 5 = Los Angeles Basin; 6 = Amargosa River; 7 = Ash Mead- ows; 8 = White-Virgin River system; 9 = Pahrump Valley; 10 = Ancestral San Joaquin River; 11 = Bouse Embayment. member as a lake, informally termed "Lake Hualapai." Note that Taylor (1983:294) re- corded P. avernalis, presently surviving in the Moapa River drainage, in the Hualapai sediments. During Pliocene time, tilting of the Sierra Nevada fault block beheaded trans-mon- tane drainage, which was diverted south- wards and formed the Owens River, which drained to the Pacific via Mohave River. Uplift began at the south, moving north- wards (Huber 1981). Various evidence in- dicates that Owens Valley was forming by 6 Ma (see above), and the present Owens drainage probably was formed by not long after that time (Fig. 11). Coastal Pyrgulopsis of the P. californiensis group were trans- ferred with the beheaded source areas, and gave rise to P. wongi. Severence of the trans- montane headwaters of the San Joaquin River is dated at 3.2 Ma; thereafter drainage was to the Mono Basin, and over the south- ern sill to the Owens River (Huber 1981). This drainage change may have allowed progenitors of the Pyrgulopsis owensensis group to invade the system from the north.3 The South Fork Kern River was tributary to the Owens Basin.4 Walker Pass, inter- 3 In addition to P. owensensis and P. wongi, two other freshwater mollusks (Helisoma newberryi [Lea], Vor- ticifex effusus [Lea]) occurred in Lahontan and Death Valley Systems during historic times (Taylor 1981). These and another three Lahontan species (Pisidium ultramontanum Prime, Valvata utahensis Call, Stag- nicola kingi [Meek]) were widespread within the latter during the Quaternary (Taylor 1985). The Tui Chub, Gila bicolor (Girard), also occurs in both areas (al- though differentiated in Owens and Mohave drainages; Miller 1973), and several other fishes of Death Valley System are closely related to Lahontan fauna (Minckley etal. 1986). - As evidenced by distribution off. giulianii. Schreck and Behnke (1971) suggested a similar drainage con- nection based on relationships of endemic Upper Kern River Valley golden trout, Salmo aguabonita Jordan. VOLUME 103, NUMBER 2 295 Fig. 13. Death Valley System and adjacent drain- ages during late Pliocene, <3 Ma, after formation of Death Valley graben and beheadal of ancestral San Joaquin drainage. 1 = Death Valley region; 2 = Owens River; 3 = South Fork Kern River; 4 = Mohave River; 5 = Los Angeles Basin; 6 = Amargosa River; 7 = Ash Meadows; 8 = White-Virgin River system; 9 = Pah- rump Valley; 10 = San Joaquin River; 11 = Bouse Embayment. preted as a wind gap in this model, is ap- proximately 700 m above the margin of In- dian Wells Valley, suggesting that drainage severence occurred no earlier than 2.5 Ma (based on uplift rates in the Deadman's Pass area; Huber 1981), and possibly more re- cently as uplift rates increased southwards. During the late Pliocene (Fig. 12), uplift of the Transverse Ranges, which enclose the present internal drainage of the Mohave Desert, resulted from compression accom- panying the northward movement of the crustal block west of the San Andreas Rift zone (Woodburne 1975). Drainage direc- tion of the Mohave River was reversed, probably with considerable dislocation, re- routing, and ponding. Drainage of the Death Valley System was shifted from the Los An- geles Basin to the Bouse Embayment. De- position in basins east of the San Bernar- dino Mountains apparently shifted from eastern-derived to western-derived sedi- ments around the Hemphillian-Blancan transition (Woodburne 1975). Late Plio- cene tilting of the Sierra Nevada block (Cole & Armentrout 1979) transferred South Fork Kern River from the Owens to the Kern system. Development of internal drainage in the Death Valley rift occurred in early Pleistocene, establishing a new base level and transferring the drainage sump of the Death Valley System from the Bouse Em- bayment to Death Valley (Fig. 13), thereby completing development of the present sys- tem.5 Acknowledgments Fieldwork was supported (in part) by Cal- ifornia Fish and Game (Contract FG7342). Bureau of Land Management (Ridgecrest Resource Area) and California Fish and Game (Bishop Office) loaned vehicles and provided other logistic support. Collecting permits were provided by State of Califor- nia and Joshua Tree National Monument. Assistance in the field was provided by J. Aardahl, M. Blymyer, J. Farrell (BLM); D. Wong (California Fish and Game); W. Cas- sidy (Fort Irwin); R. Moon and associates (Joshua Tree National Monument); D. Giu- liani, S. Denton-Pratt, and D. Sada. Mate- rial was loaned by Dr. J. McLean and C. Coney (LACM), and Drs. W. B. Miller and E. Hochberg (personal collection of former, loaned through SBMNH). The assistance of the Scanning Electron Microscopy Labo- ratory (NMNH) is greatly appreciated. M. 5 Although extensional tectonics of the Death Valley region have been extensively studied (e.g., Wernicke et al. 1988 and references cited therein), little has been published regarding drainage. Cemen et al. (1985) re- corded a late Pliocene (to 4 Ma) basin oriented roughly from north of the Black Mountains to Salt Creek, at approximately a 45? angle to the present valley. Hunt and Mabey (1966) made a convincing case for depo- sition of the "no. 2 gravel" alluvial fans, estimated at 0.5 Ma, under an external drainage regime. They con- sidered major movement of the normal fault along which the valley has been downthrown to be late Qua- ternary in age. 296 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Ryan and P. Greenhall (both NMNH, In- vertebrate Zoology) drafted maps, and pre- pared and digitized camera lucida drawings of shells, respectively. The section on his- tory of the Mohave-Death Valley region benefited from comments by D. L. Weide. Literature Cited Bachman, S. B. 1979. Pliocene-Pleistocene break-up of the Sierra Nevada-White-Inyo Mountains block and formation of Owens Valley.?Geol- ogy 6:461-463. Berry, E. G. 1948. Snails collected for the schisto- somiasis investigations. ?United States Na- tional Institute of Health Bulletin 189:55-69. Berry, S. S. 1909. The known Mollusca from San Bernardino County, California.?Nautilus 23: 73-79. Blair, W. N., & A. K. Armstrong. 1979. Hualapai Limestone member of the Muddy Creek For- mation: The youngest deposit predating the Grand Canyon, southeastern Nevada and northwestern Arizona. ? United States Geolog- ical Survey Professional Paper 1111:1-14. Cemen, I., L. A. Wright, & K. L. Verosub. 1985. Ce- nozoic sedimentation and sequence of defor- mational events at the southeastern end of Fur- nace Creek strike-slip fault zone, Death Valley region, California. Pp. 127-141 in K. T. Biddle & N. Christie-Beck, eds., Strike-slip deforma- tion, basin formation and sedimentation. ?So- ciety of Economic Palaeontologists and Min- eralogists Special Publication 37. Cole, M. R., & J. M. Armentrout. 1979. Neogene paleogeography of the western United States. Pp. 297-323 in J. M. Armentrout, M. R. Cole, & H. TerBest, eds., Cenozoic paleogeography of the western United States. ? Society of Econom- ic Paleontologists and Mineralogists, Pacific Section, Pacific Coast Paleogeography Sympo- sium 3. Dickinson, W. R. 1979. Cenozoic plate tectonics set- ting of the Cordilleran region in the United States. Pp. 1-13 in J. M. Armentrout, M. R. Cole, & H. TerBest, eds., Cenozoic paleogeography of the western United States. ? Society of Econom- ic Paleontologists and Mineralogists, Pacific Section, Pacific Coast Paleogeography Sympo- sium 3. Gilbert, C. M., M. N. Christensen, Y. Al-Rawi, & K. R. Lajoie. 1968. Structural and volcanic his- tory of Mono Basin, California-Nevada.?Geo- logical Society of America Memoir 116:275- 329. Giovannetti, D. 1979. Volcanism and sedimentation associated with the formation of southern Ow- ens Valley.?Geological Society of America An- nual Meeting Abstracts 11:79. Hannibal, H. 1912. The aquatic molluscs of southern California and adjacent regions, a transition fau- na.?Bulletin of the Southern California Acad- emy of Sciences 11:18-46. Hershler, R. 1987. Redescription of Assiminea infi- ma Berry 1947 from Death Valley, California. ? Veliger 29:274-288. . 1989. Springsnails (Gastropoda: Hydrobi- idae) of Owens and Amargosa (exclusive of Ash Meadows) River drainages, Death Valley Sys- tem, California-Nevada.?Proceedings of the Biological Society of Washington 102:176-248. , & D. W. Sada. 1987. Springsnails (Gastro- poda: Hydrobiidae) of Ash Meadows, Amar- gosa Basin, California-Nevada.?Proceedings of the Biological Society of Washington 100: 776-843. , & F. G. Thompson. 1987. North American Hydrobiidae (Gastropoda: Rissoacea): Rede- scription and systematic relationships of Tryo- nia Stimpson, 1865 and Pyrgulopsis Call and Pilsbry, 18 86.-Nautilus 101:25-32. Hubbs, C. L., & R. R. Miller. 1948. Correlation be- tween fish distribution and hydrographic history in the desert basins of western United States. Pp. 17-166 in The Great Basin, with emphasis on Glacial and Postglacial times.?Bulletin of the University of Utah 38, Biological Series 10. Huber, N. K. 1981. Amount and timing of uplift and tilt of the central Sierra Nevada?Evidence from the upper San Joaquin Basin. ?United States Geological Survey Professional Paper 1197:1- 28. Hunt, C. B., & D. R. Mabey. 1966. Stratigraphy and structure, Death Valley, California. ? United States Geological Survey Professional Paper 494A:1-162. Kilbourne, R. T., C. W. Chesterman, & S. H. Hood. 1980. Recent volcanism in the Mono Basin- Long Valley region of Mono County, Califor- nia.?California Division of Mines and Geol- ogy, Special Report 150:7-22. Miller, R. R. 1973. Two new fishes, Gila bicolor sny- deri and Catastomusfumeiventris, from the Ow- ens River basin, California. ? Occasional Papers of the Museum of Zoology, University of Mich- igan 667:1-19. Miller, W. J. 1928. Geology of Deep Spring Valley, California.?Journal of Geology 36:510-525. Minckley, W. L., D. A. Hendrickson, & C. E. Bond. 1986. Geography of western North American freshwater fishes: Description and relationships to intracontinental tectonism. Pp. 519-613 (+ bibliography) in C. H. Hocutt & E. O. Wiley, VOLUME 103, NUMBER 2 297 eds., The zoogeography of North American freshwater fishes. John Wiley and Sons, New York. Nilsen, T. H., & E. H. McKee. 1979. Paleogene pa- leogeography of the western United States. Pp. 257-276 in J. M. Armentrout, M. R. Cole, & H. TerBest, eds., Cenozoic paleogeography of the western United States.?Society of Econom- ic Paleontologists and Mineralogists, Pacific Section, Pacific Coast Paleogeography Sympo- sium 3. Parent!, L. R. 1981. A phylogenetic and biogeograph- ic analysis of cyprinodontiform fishes (Teleos- tei, Atherinomorpha).?Bulletin of the Ameri- can Museum of Natural History 168:335-557. Quade, J., & W. L. Pratt. 1989. Late Wisconsin groundwater discharge environments of the southwestern Indian Springs Valley, southern Nevada. ?Quaternary Research 31:351-370. St. Amand, P., & G. R. Roquemore. 1979. Tertiary and Holocene development of the southern Sier- ra Nevada and Coso Range, California.?Tec- tonophysics 52:409-410 (abstract). Schreck, C. B., & R. J. Behnke. 1971. Trouts of the upper Kern River Basin, California, with ref- erence to systematics and evolution of western North American Salmo. ?Journal of the Fish- eries Research Board of Canada 28:987-998. Smith, G. R. 1966. Distribution and evolution of the North American catostomid fishes of the genus Pantosteus subgenus Catostomus. ? Miscella- neous Publications of the Museum of Zoology, University of Michigan 129:1-132. Stearns, R. E. C. 1893. Report on land and freshwater shells collected in California and Nevada by the Death Valley Expedition, including a few ad- ditional species obtained by Dr. C. Hart Mer- riam and assistants in parts of the southwestern United States. ? North American Fauna 7:269- 283. Taylor, D. W. 1954. Nonmarine mollusks from the upper Miocene Barstow Formation, Califor- nia.?United States Geological Survey Profes- sional Paper 254G67-80. . 1981. Freshwater mollusks of California: A distributional checklist.?California Fish and Game 67:140-163. . 1983. Late Tertiary mollusks from the lower Colorado River Valley.?University of Michi- gan, Museum of Paleontology Contribution 26: 289-298. . 1985. Evolution of fresh water drainages and molluscs in western North America. Pp. 265- 321 in C. J. Hocutt & A. B. Leviton, eds., Late Cenozoic history of the Pacific Northwest.? American Association for the Advancement of Science, San Francisco, California. . 1987. Fresh-water molluscs from New Mex- ico and vicinity.?New Mexico Bureau of Mines & Mineral Resources Bulletin 116:1-50. Wernicke, B., G. J. Axen, & J. K. Snow. 1988. Basin and range extensional tectonics at the latitude of Las Vegas, Nevada.?Geological Society of America Bulletin 100:1738-1757. Woodburne, M. O. 1975. Cenozoic stratigraphy of the Transverse Ranges and adjacent areas, southern California. ?Geological Society of America Special Paper 162:1-91. (RH) NHB STOP 118, Department of In- vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC. 20560; (WLP) Museum of Natural History, University of Nevada, Las Vegas, 4505 Maryland Parkway S, Las Vegas, Nevada 89154. Appendix Localities visited. Data are name of site, county, state, township and range coordinates, elevation of site, and date of visitation. I. Walker Basin and environs. Cedar Creek (un- named on topo sheet), Stinkard Valley, Mono Co., CA; T 8N, R 22E, NE 'A sec. 9, 2025 m, 7-12-88.-"Tin Cup" Spring, Mono Co., CA; T 9N, R 22E, NW Vt sec. 20, 1928 m, 7-12-88.?Spring in unnamed canyon, Slinkard Valley, Mono Co., CA; T 9N, R 22E, SE >A sec. 19, 2050 m, 7-12-88.-Springs by cabin, Slinkard Valley, Mono Co., CA; T 8N, R 22E, NE 'A sec. 9, 1983 m, 7-12-88. ?Springs in SE corner of Slinkard Valley, Mono Co., CA; T 8N, R 22E, SW 'A sec. 15, 2135 m, 7-12-88. ?Springs in SE corner of Slinkard Valley (ca. 75 m SE of above), Mono Co., CA; T 8N, R 22E, SW % sec. 15, 2135 m, 7-12-88.-Springs en- tering small creek in northern Little Antelope Valley, Mono Co., CA; T 8N, R 22E, SE 'A sec. 13, 1684 m, 7-12-88.?Springs in meadow in northern Little An- telope Valley, Mono Co., CA; T 8N, R 23E, NW 'A sec. 19, 1684 m, 7-12-88.-Spring N of Camp Ante- lope, Mono Co., CA; T 8N, R 23E, NE 'A sec. 16, 1708 m, 7-14-88. ?Leakage from holding tank (of spring), Spring Creek Canyon, Mono Co., CA; T 8N, R 23E, SW 'A sec. 23, 1952 m, 7-13-88.-Spring zone along E side of West Walker River in canyon, Mono Co., CA; T 6N, R 23E, NE 'A sec. 9, 2013 m, 7-13-88.- Spring zone along W side of Little Walker River up- stream from above, Mono Co., CA; T 6N, R 23E, SW 'A sec. 15, 2050 m, 7-12-88.-Brownie Creek, Mono Co., CA; T 6N, R 22E, SW >A sec. 27, 2184 m, 7-13- 88. ?Spring by Cloudburst Creek, Mono Co., CA; T 6N, R 22E, NE 'A sec. 27, 2159 m, 7-13-88.-Spring 298 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON at Marine Corps Center, Mono Co., CA; T 6N, R 22E, NW 'A sec. 24, 2080 m, 7-13-88.-Seeps along Junc- tion Creek, Mono Co., CA; T 6N, R 23E, NE >A sec. 20, 2098 m, 7-12-88.-Spring along E side of Little Walker River, Mono Co., CA; T 5N, R 23E, NE >A sec. 4, 2263 m, 7-14-88. ? Burcham Creek, Mono Co., CA; T 6N, R 23E, NW 'A sec. 11, 2257 m, 7-12-88.- Stream along Burcham Flat Road, Mono Co., CA; T 6N, R 23E, SW 'A sec. 14, 2211 m, 7-12-88.-Fales Hot Springs, Mono Co., CA; T 6N, R 23E, SE 'A sec. 24, 2227 m, 7-12-88.?Stream, Yaney Canyon, Mono Co., CA; T 5N, R 24E, SE 'A sec. 15, 2098 m, 7-12- 88.?Spring W of Bridgeport Ranger Station, Mono Co., CA; T 5N, R 24E, NW 'A sec. 23, 2098 m, 7-12- 88.-Spring just S of above, Mono Co., CA; T 5N, R 24E, NW 'A sec. 23, 2074 m, 7-13-88.-Buckeye Hot Spring (seepage), Mono Co., CA; T 4N, R 24E, NE 'A sec. 4, 2166 m, 7-13-88. ?Seepage along Buckeye Creek, Mono Co., CA; T 4N, R 24E, NW 'A sec. 4,2166 m, 7-13-88.-Spring N of Twin Lakes, Mono Co., CA; Matterhorn Peak, CA (15), T 4N, R 24E, NW 'A sec. 28, 2318 m, 7-13-88. ?Summers Creek and springs in Summers Meadows, Mono Co., CA; T 3N, R 25E, NW 'A sec. 6, 2172 m, 7-13-88. ?Stream from Cameron Canyon, Mono Co., CA; T 3N, R 25E, NE 'A sec. 6, 2135 m, 7-13-88.-Spring SW of Little Bodie Mine, Mono Co., CA; T 3N, R 25E, SW 'A sec. 1, 2306 m, 7-11-88. ?Spring ca. 0.4 km NE of above, Mono Co., CA; T 3N, R 25E, SW 'A sec. 1, 2306 m, 7-11-88.- Warm Springs, Mono Co., CA; T 4N, R 26E, SW 'A sec. 16, 2342 m, 7-11-88.-The Hot Springs, Mono Co., CA; T 4N, R 25E, NW 'A sec. 9, 2013 m, 7-11- 88.-Travertine Springs, Mono Co., CA; T 5N, R 25E, SW 'A sec. 34, 2050 m, 7-11-88.-Small springs along East Walker River NW of Bridgeport, Mono Co., CA, between 1952-2013 m: seep with pool, E side of river, T 6N, R 25E, NW 'A sec. 26; piped spring on W side of river, T 6N, R 25E, NW 'A sec. 23, 7-11-88; seep on E side of river, T 6N, R 25E, SE >A sec. 14, 7-13- 88; spring W of river and just N of Murphy Creek, T 6N, R 25E, NE 'A sec. 14, 7-14-88; seeps (2) on steep hill along E side of river, T 6N, R 25E, SW 'A sec. 12, 7-13 and 14-88; small seeps on W side of river, T 6N, R 25E, SW 'A sec. 12. ?Spring at Wiley Ranch, Lyon Co., NV; T 8N, R 25E, NW 'A sec. 5, 1922 m, 7-11- 88. II. Mono Basin. Springs SW of Conway Summit, Mono Co., CA; T 2N, R 25E, NE 'A sec. 2,2318 m, 11-8-88. III. Adobe Valley and environs. Spring, Pizona, Adobe Valley, Mono Co., CA; T IN, R31E, SE 'A sec. 4, 2135 m, 5-27-89.-Upper Pizona Spring, Adobe Valley, CA; T IN, R 31E, SW 'A sec. 11, 2227 m, 5-27-89. ?Huntoon Spring, Huntoon Valley, NV; Huntoon Valley, NV-CA (15) (sections unplated), 11.4 km NW from SE corner of quadrangle, 1891 m, 5-28- 89. IV. Fish Lake Valley. Springs ca. 2.4 km SW of The Crossing, Esmeralda Co., NV; T IS, R 36E, SW 'A sec. 16, 1449 m, 7-16-88.-SpringjustNE of The Crossing, Esmeralda Co., NV; T IS, R 36E, NE 'A sec. 10, 1449 m, 7-16-88. ?Springs at Dyer Ranch, Esmeralda Co., NV; T 2S, R 35E, SE 'A sec. 13, 1440 m, 7-16-88.- Spring W of cemetery, Esmeralda Co., NV; T 2S, R 35E, SW 'A sec. 24, 1458 m, 7-16-88.-Seep in canyon WSW of Dyer School, Esmeralda Co., NV; Mt. Bar- croft, CA-NV (15), 12.5 km SE of NW corner of quad- rangle, 1684 m, 7-16-88. ?Cottonwood Creek, Inyo Co., CA; T 6S, R 37E, NW 'A sec. 5, 1708 m, 7-16- 88. V. Owens Basin. Spring in West Queen Canyon, Mineral Co., NV; T IN, R 32E, SW 'A sec. 16, 2013 m. ?Truman Spring, Mineral Co., NV; T IN, R 32E, SW 'A sec. 7, 2166 m. ?Spring NW corner of Round Valley, Inyo Co., CA; T 5S, R 3IE, NW >A sec. 25, 1800 m. ? Spring, SW corner of Round Valley, Inyo Co., CA; T 6S, R 31E, SE 'A sec. 31, 1586 m, 8-12- 88.-Springs, Marble Canyon, Inyo Co., CA; T 7S, R 35E, SE 'A sec. 35, SW 'A sec. 36, 1891-2074 m.- Spring, 1.2 km NW of Big Pine Spring, Inyo Co., CA; T 9S, R 33E, NW 'A sec. 16, 2074 m, 5-14-88.-Spring at McMurry Meadows, Inyo Co., CA; T I OS, R 33E, NW 'A sec. 22, 2044 m.-Spring on N side of Red Mountain, T US, R 34E, SE 'A sec. 31, 1403 m.- Spring in canyon north of McGann Springs, Inyo Co., CA; Mt. Pinchot, CA (15), 13.6 km NW of SE corner of quadrangle. ?McGann Springs, Inyo Co., CA; T 13S, R 34E, NW 'A sec. 4, 1708 m, 5-21-89.-Tub Springs, Inyo Co., CA; T 13S, R 34E, SE 'A sec. 17, 1952 m, 4-30-89. ?Spring, 0.1 km N of Independence Creek, Inyo Co., CA; T 13S, R 34E, SW 'A sec. 21, 1830 m, 6-21-88.-Springs SW of Lone Pine, Inyo Co., CA; T 16S, R 36E, SE 'A sec. 2, 1952 m, 4-29-89.-Spring at Lower Diaz Creek, Inyo Co., CA; T 16S, R 36E, SE >A sec. 5, 1312 m, 4-29-89.?Springs at Upper Diaz Creek, Inyo Co., CA; Lone Pine, CA (15), 10.3 km NE from SW corner of quadrangle, 1830 m, 5-27-89. ?Spring in canyon 1.6 km S of Carrol Creek, Inyo Co., CA; Lone Pine, CA (15), 7.5 km SW from NE corner of quadrangle, 1617 m, 5-9-89. ?Stream, Talus Canyon, Inyo Co., CA; Monache Mtn., CA (15), 10 km NNW from SE corner of quadrangle, 1830 m, 10-2-88.? Stream, Tunawee Canyon, Inyo Co., CA; Monache Mtn., CA (15), 7.5 km NNW from SE corner of quad- rangle, 1769 m, 3-28-88. ?Stream, Sacatar Canyon, Inyo Co., CA; T 23S, R 37E, sees. 3-4, 1769-1830 m, 5-18-88. VI. Indian Wells Valley. Stream, Ninemile Canyon, Inyo Co., CA; Lamont Peak, CA (7.5), 2.1 km SSW from NE corner of quadrangle, 1769 m, 7-18-88.? Stream, Grapevine Canyon, Inyo Co., CA; T 25S, R 37E, NE >A sec. 23, 1281 m, 4-14-88.-Stream, Short Canyon, Inyo Co., CA; T 25S, R 38E, SW 'A sec. 31. VII. Mohave Basin and envions. Spring, Cow Can- VOLUME 103, NUMBER 2 299 yon, Kern River Valley, Kern Co., CA; Walker Pass, CA (7.5), 5.0 km WSW from NE corner of quadrangle, 1330 m, 11-4-88.-Canebrake Creek, Kern River Val- ley, Kern Co., CA; T 25S, R 36E, SW 'A sec. 14, 1086 m, 11-4-88. ?Spring, Spring Canyon, Kern River Val- ley, Kern Co., CA; T 25S, R 36E, SE 'A sec. 34, 1171 m, 11-4-88.-Brown Spring, Kern Co., CA; T 27S, R 35E, NW 'A sec. 5, 946 m, 11-4-88.-Kelso Creek, SW of Rocky Point, Kern Co., CA; T 27S, R 35E, NW 'A sec. 20, 988 m, 11-4-88. ?Horse Canyon Spring (and spring just to E), Kern Co., CA; Horse Canyon, CA (7.5), 7.6 km SSW of NW corner of quadrangle, 1464 m, 7-18-88.-Bird Spring (dry), Kern Co., CA; Horse Canyon, CA (7.5), 4.1 km ENE of SW corner of quad- rangle, 1208 m, 7-18-88.-Frog Spring, Kern Co., CA; T 28S, R 35E, NE 'A sec. 10, 1196 m, 11-4-88.-Shoe- maker Spring, Kern Co., CA; T 28S, R 35E, center of section 12, 1452 m, 11-4-88. ? Butterbredt Spring, Kern Co., CA; T 29S, R 36E, SE 'A sec. 28, 1281 m, 11-3- 88.-Spring, Poleline Canyon, Kern Co., CA; T 30S, R 37E, NE 'A sec. 8, 854 m, 11-3-88.-Alphie Spring, Kern Co., CA; T 29S, R 36E, SE >A sec. 35, 964 m, 11-3-88. ?Spring, Hoffman Canyon, Kern Co., CA; T 30S, R 36E, SW 'A sec. 3, 1098 m, 11-3-88.-Sweet- water Spring, Kern Co., CA; T 32S, R 34E, SE 'A sec. 14, 1388 m, 7-20-88.-Springs S of Proctor Lake, Kern Co., CA; T 32S, R 34E, S Vi sec. 32, 1257 m, 7-20-88.- Spring, Bean Canyon, Kern Co., CA; T ION, R 14W, SW 'A sec. 4, 1238 m, 11-3-88.-Indian Spring, Los Angeles Co., CA; T 7N, R 14W, SE 'A sec. 18,891 m, 7-21-88. ?Little Rock Creek, ca. 8 km upstream from dam, Los Angeles Co., CA; Juniper Hills, CA (7.5), 5.7 km NNE from SW corner of quadrangle, 1159 m, 11- 5-88. ?Pallet Creek, Big Rock Creek, Los Angeles Co., CA; T 4N, R 9W, SW 'A sec. 6, 1086 m, 7-21-88.- Icy Springs, Los Angeles Co., CA; T 3N, R 9W, NE VA sec. 1, 1757 m, 11-5-88. ?Spring, Sawmill Canyon, Los Angeles Co., CA; T 3N, R 8W, NE 'A sec. 11, 2074 m, 11-12-88. ?Spring, Grapevine Canyon, San Ber- nardino Co., CA; T 4N, R 2W, NW 'A sec. 26, 1147 m, 11 -6-88. ? Rabbit Springs, San Bernardino Co., CA; T 4N, R 1W, NW 'A sec. 11, 885 m, 7-21-88.-Broad- bent Spring (unnamed on topo sheet), San Bernardino Co., CA; T 3N, R IE, NW 'A sec. 3, 1144 m, 7-21- 88.?Cushenbury Springs, San Bernardino Co., CA; T 3N, R IE, NE 'A sec. 10, 1251 m, 7-21-88.-Cotton- wood Spring (dry), San Bernardino Co., CA; T 4N, R 2E, SE 'A sec. 25, 970 m, 7-21-88.-Spring NW of Old Woman Springs (dry), San Bernardino Co., CA; T 4N, R 3E, NE 'A sec. 31, 976 m, 7-22-88.-Old Woman Springs, San Bernardino Co., CA; T 4N, R 3E, NE 'A sec. 31, 985 m, 7-22-88.-Two Hole Spring, San Ber- nardino Co., CA; Old Woman Springs, CA (15), 11.1 km NE of SW corner of quadrangle, 1165 m, 7-22- 88. ?Spring zone SW of Big Bear Ranger Station, San Bernardino Co., CA; T 2N, R IE, NW 'A sec. 17, 2074 m, 7-21-88. ?Springs SW of Fawnskin, San Bernar- dino Co., CA; T 2N, R 1W, SW 'A sec. 14, 2089 m, 7-21-88. ?Mill Creek at Thurman Flats Picnic Area, San Bernardino Co., CA; T IS, R 1W, NE 'A sec. 8, 1074 m, 7-27-88. ?Little Morongo Creek, below Mo- rongo Lakes, CA; T IS, R 4E, SE 'A sec. 24, 756 m, 11-11-88. ?Spring, Big Morongo Canyon (upper por- tion), San Bernardino Co., CA; T IS, R 4E, SE 'A sec. 18, 1110 m, 11-6-88. ?Springs, Big Morongo Canyon (lower portion), San Bernardino Co., CA; T IS, R 4E, SE 'A sec. 28, 744 m, 11-10-88.-Spring, Smith Water Canyon, Riverside Co., CA; T 2S, R 7E, NW 'A sec. 5, 1293 m, 11-10-88.-Fortynine Palms Oasis, San Bernardino Co., CA; Queen Mtn., CA (7.5), 3.1 km SE of NW corner of quadrangle, 854 m, 11-10-88.- Garlic Spring, San Bernardino Co., CA; T 13N, R 3E, SW 'A sec. 11, 708 m, 4-9-86.-Mohave River, Alton Canyon, San Bernardino Co., CA; T 1 IN, R 5E, SW 'A sec. 13, 428 m, 4-10-86.-Seepage, W side of Soda Lake, San Bernardino Co., CA; T 12N, R 8E, NW 'A sec. 2, 290 m, 7-22-88.-Old Mormon Spring (dry), San Bernardino Co., CA; Avawatz Pass, CA (15), 1.8 km NNW of SE corner of quadrangle, 634 m, 11-9- 88.?Snake Spring, Granite Mtns., San Bernardino Co., CA; T 8N, R 13E, SE 'A sec. 5, 1220 m, 11-7-88.- Cottonwood Spring, Granite Mtns., San Bernardino Co., CA; T 8N, R 13E, NW 'A sec. 7, 1366 m, 11-7- 88.?Arrowhead Spring, Providence Mtns., San Ber- nardino Co., CA; T 9N, R 13E, SE 'A sec. 22, 1208 m, 11-7-88.-Van Winkle Spring, San Bernardino Co., CA; T 8N, R 13E, NW 'A sec. 23, 1098 m, 11-8-88.- Goldstone Spring, Mid Hills, San Bernardino Co., CA; T ION, R 14E, SW'Asec. 31, 1415 m, 11-8-88.-Live Oak Spring, Mid Hills, San Bernardino Co., CA; T 13N, R 13E, NW 'A sec. 19, 1568 m, 11-7-88.-Key- stone Spring, Mid Hills, San Bernardino Co., CA; T 14N, R 16E, NW 'A sec. 29, 1781 m, 7-23-88.-Dove Spring (dry), New York Mtns., San Bernardino Co., CA;T 15N, R 17E, SW'Asec. 19, 1452 m, 7-23-88.- Pachalka Spring, Clark Mtn., San Bernardino Co., CA; T 17N, R 12.5E, NE 'A sec. 36, 1488 m, 7-23-88.- Ivanpah Springs, Clark Mtn., San Bernardino Co., CA; T 17N, R 13E, SE 'A sec. 24, 1269 m, 7-23-88.-Bonan- za Spring, Clipper Mtns., San Bernardino Co., CA; T 7N, R 15E, NW 'A sec. 22, 634 m, 1 l-14-88.-Piute Spring, San Bernardino Co., CA; T 12N, R 18E, NW 'A sec. 24, 915 m, 7-25-88. VIII. Amargosa Basin and environs. Choppo Spring, Inyo Co., CA; T 2IN, R 7E, SE 'A sec. 2, 610 m, 7-25-88.-Tule Spring (dry), California Valley, San Bernardino Co., CA; Tecopa, CA (15), 8.8 km NNW of SE corner of quadrangle, 720 m, 7-25-88. ?Beck Spring, Kingston Range, San Bernardino Co., CA; T 20N, R 10E, NE 'A sec. 31, 1354 m, 7-25-88.-Cold Creek, Clark Co., NV; T 18S, R 55E, NE 'A sec. 1, 1867 m, 9-5-77. -Willow Creek, Clark Co., NV; T 18S, R 55E, NE 'A sec. 2, 1830 m, 7-31-77.