PLIOLOPHUS 



327 



ing ramus which give the extent of attachment of the biting 

 (temporal) and grinding (masseteric and pterygoid) muscles 

 respectively. In the shape of the mandible Pliolophus most 

 resembles Tajrirus among existing Mammals, and the Palcco- 

 th&riwm among the extinct ones in which that shape is known. 

 As in almost every species of eocene quadruped yet discovered, 

 the Plioloplms presents the type-dentition of the placental 

 diphyodont series, viz. — 



. 3—3 1—1 4—4 3-3 , , * 



* 3=3' C 1-V P 4-4' m 3=3 = 44 ' 



The incisors are preserved in the lower jaw with marks of 

 attrition on their crowns demonstrating corresponding teeth 

 of the same number (six), and of similar size, in the upper 

 jaw, from which the alveolar part of the premaxillaries had 

 been broken away. 



The canines are small in both jaws : they are separated by 

 a vacant space from the outer incisors, and by a longer inter- 



Pt 



mt 



m 2. 



^^RSP ' 



Fig. 95. 

 True molars, upper jaw (twice nat. 

 size), Pliolophns. 



Fig. 96. 

 True molars, lower jaw (twice 

 nat. size), Pliolophus. 



val from the first premolars. These form a continuous series 

 with the remaining teeth in the upper jaw, but are separated 



* See Ency. Brit., art. Odontology, vol. xvi., p. 478, for tbe " Homologies 

 of the Teeth," and explanation of their symbols. 



