I 



THE HTEACOIDEA. 433 



Part of fhc. articular facet for the mandible is formed by 

 the jiigal, which extends forwards until it comes into 

 contact with the lackrymal bone. The base of the external 

 pterygoid process is perforated by a canal, as in Perisso- 

 dadyla and Lemuridce. There are large pre- and post- 

 tympanic processes, and the post-tympanic is much shorter 

 than the par-occipital process. The premaxillse are large. 

 and unite extensively with the nasal bones; the perpen- 

 dicular ramiis of the mandible is very wide, and somewhat 

 like that of the Tapii- in shape. The posterior margin of 

 the bony palate is opposite the anterior edge of the last 

 molar tooth. 



The scapula is devoid of an acromion process, as in the 

 Ferissodactyla. There are no clavicles, but the coracoid 

 process is well developed. The ulna is complete, and a 

 rudiment of the pollex is present. In the carpiis, a line 

 prolonging the axis of the third metacai-pal bisects the os 

 magnum and the hmare, which is not the case in any 

 Ungulate Mammal. 



In the hind limb, the femur possesses a small third tro- 

 chanter, which is not nearly so conspicuous as in some 

 Rodents. The tibia and fibula are complete. The ex- 

 tremity of the inner malleolus articulates with a shelf -like 

 process of the astragalus, the distal face of which bone has 

 on facet for the cuboid. The digits i. and v. are not repre- 

 sented even by rudiments. The terminal phalanx of ii. is 

 longitudinally cleft. 



[■he dentition of the adult is i. -— - c. — p.m. — , and 



2*2 ■ -^ 4*4 



3 • 3 ^_^ 



m. -g— . The outer upper incisors are very small, and soon 

 fall out ; the inner, which are very large, cm-ved, and have 

 a thick coat of enamel on their anterior faces, continue to 

 grow throughout life, as in Rodents. The lower incisors 

 have crowns denticulated at the edges, Hke those of Galeo- 

 pithecus and some Bats. They bite upon a callous pad 

 which lies behind the upper incisors. The patterns of the 

 upper and lower molar teeth are very similar to those of 

 the corresponding teeth in Rhinoceros. As in the Horse, 



2 F 



