452 ZOOLOGY SECT. 



position. The uterus is two-horned. The placenta is non-deciduate 

 and zonary. 



This order includes only the Dugong (Halicore), the Manatee 

 (Manatus) and the recently extinct Khytina. 



ORDER 4. UNGULATA. 



Terrestrial, chiefly herbivorous, Eutheria, with the fur abundant 

 or scanty, with the terminal phalanges, on which the weight of 

 the body usually rests, nearly always invested in solid horny hoofs. 

 The teeth are heterodont and diphyodont; the canines usually 

 absent or small, and the pre-molars and molars well-developed, 

 with broad crowns having tuberculated or ridged surfaces. The 

 clavicle is absent ; the humerus has no foramen over the inner 

 condyle : the scaphoid and lunar of the carpus are always 

 distinct. The villi of the placenta are diffuse or gathered into 

 patches the cotyledons. 



SECTION 1. UNGULATA VERA. 



Ungulata in which the feet are always digitigrade, with n^ver 

 more than four functional digits. The os magnum of the carpus 

 articulates with the scaphoid. The testes are contained in a 

 scrotum. The teats are usually four, and situated far back, 

 never exclusively thoracic in position. The uterus is two-horned, 

 The allantois is large ; the placenta is non-deciduate, and the villi 

 diffuse or gathered into cotyledons. 



This section comprises all the typical Ungulates. 



Sul-order a. Perissodactyla. 



Ungulata vera in which the third toe of both manus and pes 

 is larger than the others and symmetrical in itself, and in which 

 there is a tendency to reduction of the others. The femur has a 

 third trochanter. The tibial articular surface of the astragalus 

 is pulley-shaped ; the distal surface flat and more extensively 

 related with the navicular than with the cuboid ; the calcaneum 

 does not articulate with the fibula. The pre-molars and molars 

 are complexly folded, and the posterior pre-molars usually resemble 

 the molars in size and pattern. The stomach is simple ; the 

 ccecum large. There is never a gall-bladder. The teats are 

 situated in the groin, and the placenta is diffuse. 



This sub-order includes the Horses, Asses, and Zebras (Equid-ce), 

 the Tapirs (Tapirus), and the Rhinoceroses (Rhinoceros). 



Sub-order b. Artiodactyla. < 



Ungulata vera in which the third and fourth digits of both 

 manus and pes form a symmetrical pair, and in which the others 



