Wortman — Studies of Eocene Mammalia, etc. 197 



Art. XYII. — Studies of Eocene Mammalia in the Marsh 

 Collection, Peabody Museum ; by J. L. Wortman. (With 

 Plate VI.) 



• [Continued from p. 12 8. J 

 Limnocyon Marsh. 



Limnocyon Marsh, this Journal, August, 1872, p. 6, Separata • 

 Thinocyon Marsh, this Journal, August, 1872, p. 12, Separata ; 

 Oxycenodon Wortman, Bull. Amer. Mus. Nat. Hist., 1899, p. 145 ; 

 Telmatocyon Marsh, this Journal, May, 1899, p. 397. 



A group of small or medium-sized Creodonts ranging in time 

 from the beginning of the Bridger to the close of the Uinta 

 epoch, and, as far as known, having the following principal 

 characters: Dental formula I.f C.-f Pm.f M.f; first upper and 

 lower premolars two-rooted (except in Limnocyon dysodus) ; 

 last superior molar transverse and little reduced ; two sub- 

 equal inferior molars with internal cusps and moderate-sized 

 basin-shaped heels ; fibula articulating with calcaneum ; astrag- 

 alus moderately grooved ; femur with small third trochanter ; 

 deltoid crest of humerus reduced; distal end of humerus 

 broad, with prominent supinator ridge and an entepicondylar 

 foramen ; metapodials of fore feet short and phalanges elon- 

 gated ; carpus unknown. 



The genus Limnocyon was described by Professor Marsh in 

 August, 1872, from a series of superior teeth which, were not 

 in place in the maxillary. A second species was proposed in 

 the same paper upon a specimen consisting of both mandibular 

 rami, one of which contains the last premolar and first molar, 

 together with all the alveoli. In the same paper Professor 

 Marsh proposed a second genus, Thinocyon, upon an entire 

 left mandibular ramus, containing a few of the teeth in good 

 condition and the alveoli and roots of all the others. In June, 

 1899, I proposed the genus Oxycmodon upon a well-preserved 

 half of a skull, in which both the upper and lower teeth are 

 present. In May, 1899, Professor Marsh, upon my advice, 

 placed Limnocyon verus as synonymous with Sinopa, and pro- 

 posed for the second species L. riparius, the generic name 

 Telmatocyon. The reason for this advice was as follows : The 

 type of the genus consists of the dissociated upper teeth, in 

 which the superior molars are almost, if not quite, indistin- 

 guishable, in structure at least, from those of certain species of 

 Sinopa, and as the number in this latter group is three and no 

 two-molared type was at that time known, it was quite naturally 

 supposed that the type specimen of L. verus was a Sinopa. 



Am. Jour. Sci. — Fourth Series, Vol. XIII, No. 75. — March, 1902. 

 14 



