EXTINCT FAMILIES 



293 



Fl - 112 - A ri 8 ht 



upper molar of Mery- 



Merycopotamus. The genus Mwycopotamus of the lower Pliocene 

 of India may be regarded as an Anthracotheroid which has lost 

 the antero- median column to the upper molars 

 (Fig. 112), so that these teeth are consequently 

 quadrituberculate ; and may thus be regarded as 

 typical examples of the brachy-selenodont modifica- 

 tion of molar structure. 



Cotylopidce. The Miocene genus Cotylops (Ore- 

 odon 1 } is the type of a large American family in 

 which the upper molars are selenodont and usually 



, , i -i .L-I i 



have tour columns, while the lower canine is approxi- 



mated to the incisors and its form and function Pliocene, India. 



assumed by the first premolar. The last upper < From r * he Pal(eont - 



i i rm logia Indica.) 



premolar is simpler than the molars. I here is no 

 flange to the angle of the mandible ; and the feet have four digits. 

 The affinities of this peculiar family are probably widely spread, 

 but they may have been derived from the Anthracotheriidce. The 

 type genus has the full Eutherian dentition, but in some of the 

 more specialised forms (Cyclopidius) the upper incisors may be 

 wanting, and large vacuities occur in the lachrymal region. The 

 generalised genus Protoreodon, of the Upper or Uinta Eocene, has 

 five cusps on the upper molars, arranged as in the Anthracotheriida 1 . 

 The pollex is retained in the manus of the type genus. 



The family may be divided into subfamilies as follows : 



I. Upper molars with four columns. 



1. Orbits open, no lachrymal fossa, a diastema, the last upper 



premolar with two outer columns, outer wall of upper 

 molars concave and inclined inwards. Agriochcerinw 

 (Agriochcerus). 



2. Orbits closed, a lachrymal fossa, no diastema, the last upper 



premolar with one outer column ; outer wall of upper 

 molars flattened. Cotylopince (Cotylops, Eporeodon, Mery- 

 cochcerus, Cyclopidius, etc.) 

 II. Upper molars with five columns. Protoreontince (Protoreodon). 



Aiwplotheriidce. 

 This family in- 

 cludes several 

 Upper Eocene 

 European genera, 

 with selenodont 

 upper molars, 

 carrying five 

 columns arranged 

 as in Anthraco- 

 tlierium. One of 



FIG. 113. Restoration of Anoplotherium commune 

 (Upper Eocene). Cuvier. 



This name (Leidy, 1851) is preoccupied by Orodus (Agassiz, 1838). 



