DESCRIPTION OF A NEW SPECIES OF MASTODON,GOMPHOTHERIUM ELEGANS, FROM THE PLEISTO-CENE OF KANSAS.By Oliver P. Hay,Research As.iu.iiitc of the Carnegie In-stituti'in of Wn-:]iingto)i.
The specimen here described was found about 1908 near McPher-son, Kansas, by Mr. Frank Dillon, of the town named. It was metwith in a sand pit, at a depth of about 35 feet, in section 34, town-ship 19 north, range 3 west. The tooth was presented to the UnitedStates National Museum by Mr. Dillon.Type-speHmen.?A lower left hindermost molar, No. 8255, of theUnited States National Museum.Type-locality.?McPherson, McPherson County, Kansas.Type-formation.?Sheridan beds.Diagnosis.?The lower hinder molar furnished with six cross-crests, or five cross-crests and a large talon, a deep longitudinalmedian cleft and principal cones and accessory conules. Outer endsof valleys closed by buttresses and forming trefoils on wear. Innerends of valleys partially closed by accessory conules.Judging from the narrowness of the tooth and the fact that thecrests run across the crown somewhat obliquely, the writer concludesthat it is the lower left hindermost molar. It had not yet been cutand is therefore wholly unworn. The pulp cavity is large and theroots had not j^^et been developed. Unfortunately, in the process ofexhumation, the tooth was injured somewhat; but nevertheless it isin good condition.The length of the tooth is 217 mm.; its width at the first cross-crest, 83 mm.; at the fourth, 85 mm. It will be seen from themeasurements and the figures (pi. 26, figs. 1, 2) that the tooth is along and relatively narroAv one. There are present six cross-crests,the hindermost one being something more than a talon. The innerand the outer halves of each crest are separated by a narrow butvery deep cleft. Each half of each crest may be regarded as com-posed of two cones, the principal one and another nearer the mesialcleft. The latter does not rise quite as high as the principal coneand is separated from the latter by a cleft.To these four cones of each crest may be added accessory conules.It is probable that at a later time the median cleft and those sepa-Proceedings U. S. National Museum. Vol. 53?No. 2198. 219
220 FROCEEDIXGS OF THE NATIOXAL MUSEU}r. vol.53.rating the parts of each lateral half of the crests would have beenhidden by a deposit of cement; but a specimen of a tooth of G.foridanum in a similar stage of development has already a ratherthick layer of this.The outer cones of each crest are furnished with buttresses whicheffectually close up the transverse valleys. These buttresses aremostly composed of subsidiary conules, which cling closely either tothe parts of the principal cone or to one another. The row of conulesforming the anterior buttress of the first crest runs into the anteriorcingulum. The posterior buttress is composed of two conules, thehinder of Avhich is applied to a conule which forms the anteriorbuttress of the second crest. The hinder buttress of this secondcrest, apparently of three or four flattened conules, joins the anteriorbuttress of the third crest; but it appears to be carried also inwardand downward by a row of flattened conules between the inner halvesof the second and third crests. The posterior buttress of the thirdcrest is similarly disposed, as is also that of the fourth crest. Thehinder buttress of the fifth crest is less completely developed.On wear the outer halves of the three anterior crests would pro-duce each a trefoil: the succeeding two would form less completeones.There is a tendency for the formation of buttresses on the cones ofthe inner half of the tooth. In the first transverse valley the innerbuttresses are nearly as complete as the outer ones. In the secondtransverse valley there is an accessory conule attached to the frontof the third crest, but none to the rear of the second crest ; nor arethere buttresses on the succeeding crests. At the inner end of thefirst transverse valley there is a very large tubercle. There was asimilar one at the inner end of the fourth valley.The injuries done to the tooth make it difficult to speak with con-fidence regarding the cingulum, but this appears to have been presentalong the outer face of the tooth. At the outer end of each valleythere is a cluster of small tubercles, and these appear to have metacross the base of the outer cones.The tooth here described resembles somewhat the correspondingone of Gomyliotlienum tropicum (Cope), of the Blanco Pliocene:but in the McPherson tooth there are a greater subdivision of theprincipal cones and a larger number of accessory conules in thevalleys. It is also not greatly unlike the corresponding tooth ofGomphotheriiim foridanum^ likewise a Pliocene species. The latter,however, very larely develops buttresses on both halves of the crests:and it appears to have had properly only four cross crests and atalon. Likewise, the principal cones of G. f^oridanum appear to bemore obtuse than those of G. elegans.
NO. 2198. A NEW SPECIES OF MASTODUX?HAY. 221The region about McPherson is covered by deposits which belongto the Sheridan, or Equus, beds. We ha^-e in this tooth, therefore,evidence that the bunolophodont mastodons continued on into thePleistocene. This is confirmed by the discovery of an upper secondmolar probably of this species and of a maxilla with two teeth ofanother species in the Pleistocene of Texas. The latter will bedescribed and figured elsewhere.The upper second molar mentioned above belongs to the rightside. The tooth is in the collection of Baylor University, at Waco,Texas. It was found in Pleistocene deposits on Hog Creek, McLen-nan County, near Speegleville, a town about 8 miles west of Waco.The crown is practically complete, but the roots are missing. Thelength is 145 mm., the width 90 mm. There are three crests and alarge talon. The wear on the two anterior crests has produced onthe inner half of each a large trefoil. Where the enamel of thesetrefoils joins the outer cones it is considerably folded. There arevery distinct buttresses on the outer halves of the crests, especiallyof the first and second. The anterior buttress of the second crest isdouble.This tooth is larger than the corresponding one of any other masto-don known to the writer ; but its size corresponds to that of the typetooth. Its complication is greater than in the hinder molar, but thatmight be expected. This tooth resembles somewhat those whichCope ^ has referred to G. hu7nboldii; but the crests are not so closelyappressed and the enamel is not so strongly folded. The tooth de-scribed by Cope belonged to the Blanco Pliocene.EXPLANATION OF PLATE 26.Gomphotherim elegans. X \.
Figs. 1, 2. Lower third molar found at McPlierson, Kansas.Fig. 3. Upper second molar found near Waco, Texas.14th Ann. Rep. Geol. Surv. Texas, p. 60, pis. 16, 17.

U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 53 PL. 26
GOMPHOTHERIUM ELEGANS.For explanation of plate see page 221.