Wortman — Studies of Eocene Mam?nalia. 



133 



124 



Art. X. — Studies of Eocene Mammalia in the Marsh Collec- 

 tion^ Pedbody Museum y by J. L. Wortman. . 



[Continued from vol. xvii, p. 33.] 



Omomys pucillus Marsh. 

 Hemiacodon pucillus Marsh, this Journal, 1872, p. 22, Separata. 



The type of this species, figure 124, consists of a fragment of 

 a right mandibular ramus bearing the second molar, the struc- 

 ture of which agrees very closely with that of the corresponding 

 tooth of 0. Carteri, but the former is distinctly smaller. A 

 second jaw fragment in which the 

 second and third molars are pre- 

 served undoubtedly belongs to the 

 same species. In my own collec- 

 tion, there are two jaw fragments 

 in association with two superior 

 molars, and in the Marsh collection 

 there is one entire series of superior 

 molars. These additional speci- 

 mens, figures 125 and 126, furnish 

 as complete a knowledge of the 

 dentition as that described in the 

 foregoing species. The dental for- 

 mula of the lower jaw is the same F * G . U ? E 124. -Jaw fragment 



s\ n . * V ..i j? containing the lower molar of 



as m O. Carter^ and with some tew the right side of Omomys pucillus 



exceptions, which are of no more Marsh (type of Hemiacodon pu- 



than specific importance, the details cillus Marsh) ; side and crown 



x , , x • m nM views : a little more than four 



of structure are very similar. The times ^ atural size 

 chief distinctions separating 0. 



125 



Figure 125. — Lower jaw and two superior molars of Omomys pucillus 

 Marsh ; side view of lower jaw, with side and crown views of teeth, and 

 crown view of superior molars ; the last are represented in outline five times 

 natural size, while the lower jaw is a little less than three times natural size, 

 and is drawn from three specimens. 



pucillus from 0. Carteri are the following : The species is con- 

 siderably smaller ; the last lower molar is slightly more reduced, 



