342 THE ANATOMY OF VERTEBEATED ANIMALS. 



Clavicles are never present. Tlie limbs have not more 

 than four complete digits. The ungual phalanges are 

 clothed in obtuse horny sheaths, which are commonly very 

 thick and go by the name of hoofs. Upon these the weight 

 of these quadrapeds is usually supported, whence they have 

 been called unguligrade. Some few, however, rest the 

 weight of the body upon the under surfaces of the pha- 

 langes, or are digitigrade. The metacarpal and metatarsal 

 bones are elongated, and take a vertical, or much inclined 

 position. 



In the female, the mammae are either few in number, 

 when they are inguinal in position ; or numerous, when 

 they are disposed in two rows along the abdomen. 



The intestine is very generally provided with a ccecum 

 of considerable size. 



The cerebral hemispheres always exhibit convolutions, 

 which are usually very numerous ; and, when the brain is 

 viewed from above, the surface of the cerebellum is largely 

 uncovered. 



The Ungulata are divisible into the Perissodactyla and 

 the Artiodactyla, thoiigh it is probable that the attempt to 

 define these groups will break down with the increase of 

 our knowledge of fossil forms. 



1. In the Perissodactyla, the number of the dorso-lumbar 

 vertebree is not fewer than twenty-two. The third digit 

 of each foot is symmetrical* in itself, and the toes of the 

 hind foot are odd in number (Fig. 93, B). The femur 

 has a third trochanter (Fig. 100-^). The two facets upon 

 the front face of the astragalus are very unequal ; the less 

 articulating with the cuboid bone. 



In the skull, the tympanic bone is small; and, as in 

 sundry other mammals, the root of the pterygoid process 

 of the sphenoid is perforated by an aperture or canal. 



The posterior premolar teeth are, generally, very like the 

 molars. The stomach is simple, and the ccecum exceedingly 

 large. 



The teats are inguinal, or situated in the groin. When 

 * Or at least very nearly so. 



