CRUSTACEANS OF THE ORDERS EUPHAUSIACEA ANDMYSIDACEA FROM THE WESTERN ATLANTICBy Walter M. TattersallProfessor of Zoology, University College, Cardiff, WalesINTRODUCTIONDr. H. B. Bigelow was good enough to submit to me for examina-tion and report the Euphausiacea and Mysidacea collected in thewest Atlantic by the United States Coast Survey steamer Bache inJanuary to March, 1914. The collection contained 27 species ofEuphausiacea and 11 species of Mysidacea, while from the point ofview of numbers it was an extremely large collection.The itinerary of the cruise of the Bache, together with a full accountof the oceanographical results obtained, has already been published(Bigelow, 1917a), but for the sake of convenience a list of the stationsat which Euphausians or Mysids were taken is given on pages 4-6.The area explored during this cruise has never before been sys-tematically examined for the Crustacea here reported on, althougha large number of disjointed and scattered records are to be found inliterature. Hansen (1915) has given a great many records of Euphau-siacea from the west Atlantic, mainly, however, in the northwesternpart of the area now under consideration. Ortmann (1893) recordscertain species from or near to this area, taken during the GermanPlankton Expedition, and Colosi (1920) adds a few records from theCaribbean Sea. The present collection, however, by linking uphitherto explored areas, adds considerably to our knowledge of theoccurrence and distribution of the Euphausiacea in the west Atlanticand, incidentally, and to a lesser degree, of the Mysidacea also.Only one new species was discovered, a Mysid, Ilysidopsis higelowi,from the littoral waters of Chesapeake Bay. The most interestingspecies taken by the expedition was the Mysidacean, Paralophogasterglaher Hansen, hitherto only known from the Pacific Ocean, near theDutch East Indies, and in the waters off New Zealand. Its discoveryin the western Atlantic is therefore most interesting from the pointof view of geographical distribution and demonstrates the wide rangeof this bathypelagic species. Other notable records are those of thelarvae of a large species of Thysanopoda and of the adults of Nemato-hrachion sexspinosus Hansen^ hitherto known from three specimensonly. No. 2634.?Proceedings U. S. National Museum. Vol. 69, Art. 8.3043?261 1 1
^Z PROCEEDINGS OF THE NATIONAL MUSEUM vol. eoIn attempting to summarize the results obtained by the Bache,from the point of view of the Crustacea now dealt with, one or twopoints emerge which may be noted here.1. Stations 10157-10160 are situated in a faunistic area which isquite sharply marked off from the rest of the area explored.Station 10157 is a purely littoral station characterized by thepresence of the littoral Mysids, Mysidojpsis and Neomysis. Station10160 is in the coastal waters and station 10158 on the slope wherethe tropical oceanic water and the coastal water mix. These twostations are characterized by the presence of three Euphausians,Euphausia Tcrohnii, Meganyciiphanes norvegica, and Nematoscelismegalops, the fii'st and last in great abundance. These three speciesoccurred at no other station in the whole area explored and are,moreover, northern or boreal species. At station 10160 only thesethree species occurred, but at station 10158, which is nearer to theslope, the following additional species were found: SpecimenThysanopoda monacantha 1Euphausia lenera 4Euphausia hemigibba 2Thysanoessa gregaria 66Nemaloscelis microps 1Nematobrachion boopis 1These species are members of the tropical oceanic fauna, and thehaul at station 10158 bears out in a striking way the oceanographicalresults of the cruise, in which station 10158 was found to be in theregion of the slope where the coastal and oceanic waters mix. TheEuphausian fauna at this station shows abundant evidence of thismixing of the waters, retaining, however, a predominant northern orcoastal facies.The stations 10158 and 10160 are probably on the seaward fringeof the area of distribution of Meganyciiphanes norvegica, which wouldaccount for its occurrence in such small numbers. The difference inthe relative abundance of E. krohnii and N. megalops at the twostations is probably correlated with the difference in the depth atwhich the hauls were taken. At station 10160 a haul at 100 metersyielded only 4 N. megalops to about 2,000 E. Icrohnii, while at station10158, where the haul was made at 600 meters, the numbers were 500and 2,000, respectively.2. The rest of the area, which may be called the tropical oceanicarea, represented by the hauls from stations 10161-10212, appears,at least as far as the Euphausians are concerned, to be a homogeneousuniform faunistic area. It has not been possible to say, from anexamination of the hauls, that one or another species is more abund-ant in and characteristic of any special part of the area. All thespecies appear, with greater or lesser degrees of abundance, to begenerally and widely distributed in this area.
ART. 8 CRUSTACEANS FROM WESTERN ATLANTIC TATTEESALL o
I have tried to analyze the results in order to find out if they pro-vided any information as to the vertical distribution of the Eupha\i-sians. It was obvious from the merest glance at many of the haulsthat certain genera and species were characteristic of certain zonesbut it has not been eas}^ to dem.onstrate this on paper. The explana-tion of this difficulty probably lies in the fact that the nets used forplankton were open nets and, therefore, in a haul from deep water,a certain number of specimens of upper water forms would be caugh tduring the ascent of the net. It has been impossible to decide howmuch allowance must be made for this and to eliminate this source oferror. One example will suffice to illustrate this point. Eupham-Aaamericana is clearly an upper water, if not a truly surface, speciesyet the records reveal its occurrence in small numbers in even thedeepest hauls down to 1,800 meters. One other consideration hascomplicated the question. There is a certain amount of evidenceavailable to suggest that some species of Euphausians at any rateexhibit diurnal movements, rising to the upper waters during hoursof darkness and sinking to deeper waters by daylight. I have notbeen able to take this consideration into account in the followingpages. At the same time I think it is possible to suggest with a certainmeasure of confidence the following general conclusions on the verticaldistribution of the species of Euphausians found in the collection.The species may be classified roughly into the following groupsapparently characteristic of particular zones of water:1. Species which have their maximum of abundance in the upper100 meters of the sea and are frequently taken actually at the surface:Euphausia americana. Euphausia tenera.Eriphausia brevis. Euphausia hemigibba.Euphausia mutica.2. Species which have their maximum of abundance between100-200 meters and are rarely captured at the surface:Thysanopoda tricaspidata. Thysanopoda aequalis.Thysanopoda monacantha. Euphausia gibboides.Stylocheiron carinatum. Nematobraddon flexipea.Stylocheiron suhmii.3. Species which are truly deep water with the maximum of abund-ance at depths below 200 meters:Bentheuphausia amblyops. Thysanopoda cornuta.Thysanopoda microphlhalma. Thysanoessa gregaria.Nematoscelis microps. Nematobrachion boopis.Nematoscelis tcnella. Nematobrachion sexspinosus.Stylocheiron elongatum. Stylocheiron longicorne.Stylocheiron abbreviatum. Stylocheiron maximum.These tentative suggestions are based on the evidence providedby the present material and are not opposed to anything that was pre-viously known of the vertical distributions of the species concerned.
PEOCEEDINGS OF THE NATIONAL MUSEUMData to accompany cited Bache stations, 1914
Stations
ART. 8 CRUSTACEANS FROM WESTERN ATLANTIC'?TATTERSAI.LData to accompany cited Bache stations, 1914?Continued
Stations
Northeast ProvidenceChannel:10196
Stn'its of Florida:10198. _
10200-
10202.
10203.
20204.
10205.
10206.
Date
Mr.r. 3.
Mar. 13.
Mar. 18.
Mar. 19..
Mar. 21.
10207
North of Baharriii T3ank10208
10209
Lat. N.
23 59
23 32
27 17
Mar. 22 ! 27 57
Long. W
81 60
81 48
80 03
79 52
79 40
78 46
Depth
Meters
201005001,0003,400
20ICO200400900201002C0400fiOO1,0001,40020100200300400oCO70020100200SOO4008002010015020001001752502010020030040050070020100200300400500
2010020030050070080020100200400500700800900
Salinity(per mi.l)
36.5836. 5635. 0435. 0334.9236. 1136.11
34.9035.9335.9336. 2636.5835.6635. 0334. 8736.1736.2636. 6736.4436.2635.8135.5336.0836.2636. 5335. 9935. 8434. 8536.1736. 2036.1735.30:i6. 0236.0836. 2236. 0435.4334. 8536.09;<6. 1136. 2636.5538.8235.1034.8536.1730. 1730.2036. 5636.3836. 0835.7936.4236.4436. 5136.5336.4230. 1835.3735. 0336. 4436.4536. 4936. 49156. 1135.9735.26IS.'oi
Tem-perature
'C.22.8322.8422.8212. 935.202.8623. 3523. 0620.3413. 9810.367.0024.7824.7224.4522.3413.519.108.314.3623.3523.3023.2321.8218.7116.6314.1512.1724.0324.0323.2520.1715.9514.426.1621.7521.8321.0710.7223. 6022.8822. 4819.1912.250.9023.7523.4023.4020.1314.719.688.535.7023.7023.6023.3019.9317.6115.7813.9022.8022.4219.9118.7816.3910.888.2622. 2321.5220.6518.5716.1110.087.41
PROCEEDINGS OF THE NATIONAL MUSEUMDaia to accompany cited Bache Stations, 1914 ?Continued
ttations
ART. 8 CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALL 7from L. typicus in possessing a subdorsal spine directed straightbackwards on the posterior margin of the sixth abdominal somite,at the base of the telson on each side. These spines are really presentin L. typicus but are not nearly so well developed or so prominentas in L. spinosus.Distribution.?Ortmann (1906) first made known the occurrenceof this species off the coast of North America, recording it from offthe coasts of North and South Carolina, the Gulf of Mexico and KeyWest, though Smith (1881) had earlier noted the presence ofLopliogaster off the coasts of New England, without naming thespecies. These are the only records, with which I am acquainted,from this region of the Atlantic Ocean. The Bache specimen wascaptured at a point intermediate between the Carolina stations andKey West of Ortmann's records.
2. LOPHOGASTER SPINOSUS OrtmannLophogaster spinosus Ortmann, 1906, p. 26, pi. 1, figs, la, 16.
?
Hansen,1910, p. 14.?ZiMMER, 1914, p. 382.Occurrence.?Station 10195, 100-0 m., 1 young specimen, 9.5 mm.long from the tip of the rostrum to the end of the telson.Remarlcs.?Although the specimen is so small, it exhibits all thecharacters distinctive of the species as compared with L. typicus.The median spine of the rostral plate is hardly as long as in the type-specimen and this fact was also noted by Zimmer in young specimens.On the other hand the posterolateral prolongations of the carapaceare proportionally longer than in the type, extending backwardalmost to the level of the posterior margin of the third abdominalsomite. The antennal scale has nine teeth, including the terminal,on the outer margin. The telson has altogether eight pairs of lateralspines, including the large terminal pair, and has five teeth on thepectinate apical portion. The postero-lateral free corners of thethird, fourth, fifth, and sixth abdominal pleura are acute and pro-duced into prominent spines, less produced in the third pleura thanin the others but in all cases much more produced than in L. typicus,in which the pleura of the third somite are without spines.Distribution.?The type-specimen was taken at 30? 47' 30" N.,79? 49' W., north of the Bahamas. The BacJie specimen is from alocality rather to the northeast of the Bahamas but not very farfrom the type-locality. Zimmer, however, has recorded the speciesfrom the South Atlantic, midway between South America and SouthAfrica. From the fact that the present specimen was caught in amidwater townet, it seems probable that L. spinosus, like L. typicus,is pelagic in the post-larval and young stages. In this connectionit is to be noted that one of Zimmer's specimens was caught in atownet at only 10 meters. The Bache specimen shows no traces ofpectinations on the rostral plate or abdominal pleura.
8 PROCEEDINGS OF THE NATIONAL MUSEUMGenus PARALOPHOGASTER Hansen3. PARALOPHOGASTER GLABER HansenParalophogaster glaber Hansen, 1910, p. 16, pi. 1, figs. 2a-2n.?Tattersall,1923, p. 279.Occurrence
LengthStation
CEUSTACEAJSrS FROM WESTERN ATLANTIC TATTERSALLFamily EUCOPIIDAEGenus EUCOPIA Dana4. EUCOPIA UNGUICULATA (WiUemoes-Snhm)Occurrence.?Station 10166, 1100-0 m., 1 specimen.Remarlcs.?I can find no previous record of this species from thearea explored by the Bache or indeed from the northwest Atlanticanywhere in close proximity to the coast of America.Suborder MYSIDAFamily MYSIDAESubfamily SmiELLiNAEGenus SIRIELLA Dana5. SIRIELLA THOMPSONII (H. Milne-Edwards)Occurrence
Station
10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 6?Subfamily MYSINAEGenus KATERYTHROPS Holt and Tattersall
7. KATERYTHROPS OCEANAE Holt and TattersallOccurrence.?Station 10166, depth 1,100-0 m., 2 males; station10211, depth 500-0 m., 1 immature specimen.RemarJcs.?This species has not been recorded previously from thearea under notice.Genus EUCHAETOMERA G. O. Sars8. EUCHAETOMERA TYPICA G. O. SarsOccurrence.?Station 10173, depth 200-0 m., 3 specimens; station10187, depth 200-0 m., 1 female.Remarlcs.?This widely distributed species has not actually beenrecorded before from the Bache area, but is known from the moresoutherly and tropical parts of the Atlantic.
9. EUCHAETOMERA TENUIS G. O. SarsOccurrence
Station
ART. 8 CRUSTACEANS FROM WESTERN ATLANTIC TATTEESALL HMaxillulae with a definite shoulder on the outer margin of the outerplate proximal to which are a few minute spinules; inner plate withtwo setae.Maxillae with the proximal lobe narrow; distal lobe divided intotwo parts by a short furrow; palp long, distal joint narrowly oval,nearly twice as long as broad and twice as long as the proximal joint;exopod long and narrow, setae present only on its outer margin andthe distal setae much longer than the proximal.First thoracic limbs of the normal form characteristic of the genuswith the second and third joints of the endopod fused; the limbs arerather shorter and stouter than in the European species of the genusespecially with regard to the sixth joint; seventh joint not longerthan broad; dactylus stout and straight.Second thoracic limbs with the endopod relatively enormouslydeveloped, much more robust than in any known species of the genusand as far as the present material goes, more robust in the female thanin the male ; this relative development of the limbs is attained mainlyby the large size of the sixth joint which is one-quarter longer than thefifth and four times as long as broad; it is widest just distal to themiddle and from this point the joint narrows considerably, the distalportion of the inner margin being slightly concave and armed withnumerous spiniform setae; the outer distal margins are also armedwith numerous setae; the seventh joint is about one-fourth of thelength of the sixth and terminates in a strong somewhat curved nail;the outer margin is convex and the inner margin concave and fringedalso v/ith spiniform setae; the inner face of this joint is armed withnumerous very strong setae which are barbed on one side only; theconcave inner margin of the seventh joint folds down against thedistal portion of the inner margin of the sixth joint to form a kind ofsubchela to the limb; in the male specimens, which are, however,immature, the second thoracic limbs have the same general form asin the female just described but appear to be less robust and thesubchelatc appearance of the limbs is less well marked.Remaining thoracic limbs with the sixth joint of the endopoddivided into two subjoints by a transverse suture; seventh joint veryshort and terminating in a long slender nail.Abdomen with the sixth somite one and two-thirds time as long asthe fifth.Pleopods in the only males available, which are immature, are alldistinctly biramous.Telson as long as the sixth abdominal somite, one and a third timesas long as broad at the base and three times as long as the breadthat the apex, entire and broadly linguiform in shape with the apexbroadly rounded; lateral margins with about twelve short stoutspines distributed along the whole length; apex armed with three
12 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.60pairs of long strong spines, the inner pair equal in length to one-thirdof the telson, the next pair slightly shorter and the outer pair onlyone-fifth of the telson in length; no plumose setae on the apex.Inner uropods one and a half times as long as the telson with fivespines on the inner lower margin in the region of the statocyst; outeruropods slightly longer than the inner.Length of immature specimens of both sexes, 7 mm.RemarTcs.?This species may be distinguished by the combinationof characters afforded by the unjointed antennal scale, the powerfullydeveloped endopod of the second thoracic limbs and the form of thetelson and its armature. Only one other described species of thegenus, M. acuta Hansen, possesses an unjointed antennal scale. Inall the other species the scale has a small distal portion separated offby a distinct suture. In M. acuta, however, the terminal portion ofthe scale is acutely pointed and thus differs markedly from the presentform in this respect. In the general form of the telson, M. higelowiagrees very closely with M. Jcempii Tattersall. These two specieshave a form of telson and telsonic armature quite distinct from thoseof any of the remaining species. In M. Jcempii there are four pairsof stout spines at the apex and in M. higelowi only three. M. Icempii,however, differs from M. higelowi in having a distinct distal joint to theantennal scale, in the much less robust endopod to the second thoraciclimbs and in the fact that the sixth joint of the endopods of the remain-ing thoracic limbs is three-jointed.Genus NEOMYSIS Czerniavsky11. NEOMYSIS AMERICANA (S. I. Smith)Occurrence.?Station 10157, surface, abundant.Distrihution.?This common American species has been recordedfrom several localities on the eastern coast of America from Massa-chusetts to New Jersey, but I can not trace any previous record fromso far south as the present one which is from off the coast of Virginia.It is, however, doubtless abundant in the shallower waters along thegreater part of the coast.Order EUPHAUSIACEAFamily EUPHAUSIIDAEGenus BENTHEUPHAUSIA G. O. Sars12. BENTHEUPHAUSIA AMBLYOPS (G. O. Sars)Occurrence.?Station 10182, 1800-0 meters, 1 specimen, 10 mm.long.ReinarJcs.?The single specimen is still post-larval and presents acharacter not hitherto known in the genus, namely, the posteriorhalf of the lower free margin of the carapace is serrate. Serrations
ART. 8 CIRUSTACEANS FKOM WESTERN ATLANTIC TATTEESALL. V6
oil various parts of the cuticle of Euphausians are not infrequentduring the larval and post-larval stages. They are most frequentlyfound on the anterior margin of the carapace and on the rostralplate. In some larvae which I attributed to Eu^jJiausia longirostrisHansen, however, serrations on the lower free margins of the cara-pace were present (Tattersall, 1924). The serrations on the presentspecimen of Bentheuphausia amhlyops are, I take it, the last remainsof a similar armature.Distribution.?Hansen (1915) recorded two specimens of this speciesfrom localities in the West Atlantic off the coasts of America, about7-10? north of the place at which the Bache specimen was captured.These records are the only ones v/ith which I am acquainted fromthe immediate vicinity of the area explored by the Bache.Genus THYSANOPODA H. Milne-Edwards13. THYSANOPODA TRICUSPIDATA H. Milne-EdwardsOccurrence
station
14 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 69ture form (Tattersall, 1924). I have no information as to the timesat which the hauls of the Bache were made, but the evidence pro-vided by the above records of this species would suggest that theywere made during daylight. It therefore seems possible to suggestthat T. tricuspidata is an epiplanktonic species, with a maximumoccurrence at about 100 meters during the hours of daylight, risingto the surface at night.14. THYSANOPODA MONACANTHA OrtmannOccuiTeuxe
Station
AKT. 8 CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALL, 15Analysis of the above records
Depth of net
16 PROCEEDINGS OF Till: NATIONAL MUSEUM vol.69The largest specimen measures 13 mm. in length and differs fromHansen's specimen measuring 14.5 mm. in the following points:(1) The presence of a very large and powerful spine on the lateralmargins of the carapace posterior to the center.(2) The median spine of the rostral plate is much more produced.In the first of these points it agrees with the larvae described byZimmer, which are, however, much smaller in size, measuring 5.5-10mm. The lateral spine on the carapace is probably a larval characterbut it is difficult to believe that the difference in size of this spine inmy own and Hansen's specimens can be explained entirely by thesmall difference in total length. It rather suggests that the twolarvae belong to separate species.In the second of the above points my larvae differ from those de-scribed by both Hansen and Zimmer, which are in substantialagreement in the form of the rostral plate. The figures whichaccompany this report will bring out the extent of this difference andit is only necessary to add that the rostral plate is of very much thesame form in the smallest as well as the largest specimen.I can not see any trace of ripple markings on the carapace such asare described and figured by Zimmer in his larvae and my specimensshow a further point of difference in that there is no long spine on thedorso-lateral angle of the last abdominal somite, but the epimeralplate is acutely pointed at the postero-lateral angle. In otherrespects, allowing, of course, for the different degree of developmentof the appendages due to differing age, my specimens agree fairlywell with those of Hansen and Zimmer. Particularly characteristicof my specimens is the clumsy external form and the unjointednarrowly conical flagella of the antennules and antennae. All thespecimens are from very deep water.Genus MEGANYCTIPHANES Holt and Tattersall18. MEGANYCTIPHANES NOKVEGICA (M. Sars)Occurrence.?Station 10158, 600-0 m., 1 specimen; station 10160,100-0 m., 12 specimens.Remarlcs.?The two stations at which this species occurred arein the coastal region, 10160 in purely coastal waters, 10158 in theregion of mixture between coastal and Gulf Stream water. Thefact that M. norvegica occurred only at these two stations confirmswhat was previously known of its distribution on the Atlantic coastsof America, where it is conclusively a coastal and not an oceanicGulf Stream form.
CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALl. 17Genus EUPHAUSIA Dana19. EUPHAUSIA KROHMI (Brandt)Occurrence.?Station 10158, 600-0 m., 2,000 specimens; station10160, 100-0 m., many.RemarTcs.?The distribution of this species in the area exploredby the Bache is interesting. It occurred in the same two hauls asMeganyctiphanes norvegica and in no others, being replaced in thepurely oceanic waters by the closely allied species E. americana.The enormous abundance of E. Jcrohnii at these two stations coupledwith its complete absence in all the other points suggests that possiblyit, like M. norvegica, should be regarded as a coastal and slope formrather than as an oceanic species. This, however, is not in agree-ment with previous records, for the species has frequently beenrecorded from waters which are purely oceanic. Many of Hansen'srecords (1915) from the west Atlantic off the American coast arefrom the oceanic water outside the continental shelf. Perhapsthe true explanation is that E. Jcrohnii is not so much a coastal andslope form as a boreal species representing a northern element in theplankton off the American coast. Its wide distribution in the north-ern parts of the North Atlantic from America to the EuropeanAtlantic slope off Norway and the British Isles supports this view.Its main distribution is, in fact, very similar to that of M. noi'vegicabut the latter extends much nearer into the coastal waters on bothsides of the Atlantic.
20. EUPHAUSIA AMERICANA HansenOccurrence
station
PROCEEDINGS OF THE NATIONAL MUSEUMAnalysis of the above records
Depth of net Totalnumberof hauls
Meters
-255075100150..175....200300
Numberof haulsin whichspeciesoccurred Totalnumberof speci-mens
1 1, 00022305412633101
Depth of net
Iteiers400500....6007007501,0001,1001,4001,800
^F.T. s CRUSTACEANS FROM WESTERN" ATLANTIC TATTERSALL 19Analysis of the above records
Depth of net
Meters255075...lOO...150175200300
1
1
20 PROCEEDINGS OF THE NATIONAL MUSEUMRemarJcs.?This species appears to be generally distributed in thetropical oceanic area, but is not so abundant as either E. amerieanaor E. hrevis. It occurs frequently at the surface but is also distrib-uted evenly throughout the upper 200 meters. Below this depth itis comparatively rare and occurred in no haul from a greater depththan 700 meters. 23. EUPHAUSIA TENERA HansenOccurrence
station
CRUSTACEANS FROM WESTERN ATLANTIC TAl'TERSALL, 21
24. EUPHAUSIA HEMIGIBBA HansenOccurrence
Station
22 PEOCEEDINGS OF THE N-A.TIONAL MUSEUMTtemarks.?This species is the rarest of the members of the genuscaptured by the Bache. The numbers are too few to enable anygeneralizations to be made, but it is significant that no specimenswere taken at the surface. The species appears to be most fre-quently caught between 75 and 150 meters and none were caught ata greater depth than 700 meters.Genus THYSANOESSA Brandt26. THYSANOESSA GREGARIA G. O. SarsOccurrence
Station
ART. s CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALL 23
28. NEMATOSCEUS MICROPS G. O. SarsOccurrence
Station
24 PROCEEDINGS OF THE ISTATIOISrAL MUSEUM
31. NEMATOBRACHION FLEXIPES (Ortmann)Occurrence
station
CRUSTACEANS FEOM WESTERN ATLANTIC TATTERSALL 25Genus STYLOCHEIRON G. O. Sars33. STYLOCHEIRON CARINATUM (G. O. Sars)Occuirence
Station
26 PEOCEEDINGS OF THE NATIONAL, MUSEUM34. STYLOCHEIRON ELONGATUM G. O. SarsOccurrence
station
AKT. 8 CRUSTACEANS FROM WESTERN ATLANTIC TATTERSALL 27Remarks.?This species has a distribution in the area exploredvery similar to that of S. suhmii. It is, however, rather more abun-dant than the latter and appears to have its maximum of abundancein somewhat deeper water. It occurred in only 4 out of 46 haulsmade at less than 200 meters, but in 17 out of 23 hauls between 200and 1,800 meters. It is most abundant between 200 and 500 meters.37. STYLOCHEIBON ABBREVIATUM G. O. SarsOccurrence
Station
28 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. siBiGEiiOw, H. B.?Continued.1917. Explorations of the coast water between Cape Cod and Halifax in1914 and 1915, by the U. S. Fisheries schooner Grampus. Oceano-graphy and plankton. Bull. Mus. Comp. ZooL, vol. 61, pp. 163-357, 2 pis.1917. Explorations of the United States Coast and Geodetic Survey steamerBache in the western Atlantic, January-March, 1914, under thedirection of the United States Bureau of Fisheries. Oceanography.Rep. U. S. Comm. Fisher, for 1915, App. 5, 62 pp. 1 chart.COLOSI, G.1917. Raccolte planctoniche fatte dalla R. Nave Liguria nel viaggio di cir-connavigazione del 1903-05 sotto il comando di S. A. R. Luigi diSavoia, Duca degli Abruzzi, vol. 2, fasc. 7, Crostacei, parte 2.Eufausiacei. pp. 165-205. 3 pis. Firenze.Hansen, H. J.1910. The Schizopoda of the Siboga Expedition. Siboga Reports, vol. 33pp. 123, pis. 1-16.1911. The genera and species of the Order Euphausiacea, with account ofremarkable variation. Bull. Instit. Oc6an. Monaco, no. 210, pp.54, 18 text figs.1912. The Schizopoda. Reports . . . U. S. Fish Commission . . . Alba-tross. Mem. Mus. Comp. Zool., vol. 35, pp. 175-296, pis. 1-12.1913. Report on the Crustacea Schizopoda collected by the Swedish Ant-arctic Expedition, 1901-1903, under the charge of Baron Dr. OttoNordenskjold. Copenhagen, pp. 1-56, pis. 1-6.1915. The Crustacea Euphausiacea of the United States National Museum.Proc. U. S. Nat. Mus., vol. 48, pp. 59-114, pis. 1-4.Ortmann, a. E.1893. Decapoden und Schizopoden der Plankton-Expedition. Ergebn.Plankton-exp., vol. 2, G. b., pp. 1-120, pis. 1-9.1906. Schizopod Crustaceans in the United States National Museum.?TheFamilies Lophogastridae and Eucopiidae. Proc. U. S. Nat. Mus.,vol. 31, pp. 23-54, pis. 1-2.Smith, S. I.1881. Preliminary notice of the Crustacea dredged in 64-625 fathoms oflf theSouth Coast of New England by the U. S. Fish Commission in 1880 .Proc. U. S. Nat. Mus., vol. 3, pp. 413-452.TattersALL, W. M.1923. Indian Mysidacea. Rec. Ind. Mus., vol. 24, pp. 445-504, 28 textfigs.1924. Crustacea. Part VIII.?Euphausiacea. Brit. Antarc. ("Terra Nova'')Exped., 1910. Zool., vol. 8, no. 1. pp. 1-36, 2 pis.ZiMMER, C.1914. Die Schizopoden der Deutschen Sudpolar-Expedition, 1901-1903,Deutsch. Sudpol.-exp., 1901-1903, vol. 15, pp. 377-445.

EXPLANATION OF THE PLATESPlate 1Myaidopsis higelowi, new speciesFig. 1. Anterior end, dorsal view. X 33.2. Antennal scale and peduncle. X 65.3. Maxillula. X 65.4. Maxilla. X 65.6. Endopod of first thoracic limb. X 65,6. Endopod of second thoracic limb. X 65.7. Endopod of third thoracic limb. X 65.8. Telson. X 100.30
U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 69, ART. 8 PL. I
Mysidopsis bigelowi, New SpeciesFor explanation of plate see page 30
U. S NATIONAL MUSEUM PROCEEDINGS, VOL. 69, ART. 8 PL. 2
Young Specimen of ThysanopodaFor explanation of plate see page 31
Plate 2Thysanopoda, young specimens i?cornuta Illig)Fig. 9. Lateral view of specimen 13 mm. X 10.10. Dorsal view of anterior end of the same specimen. X 10.11. Telson and uropods of the same specimen. X 25. 31O