252 



VERTEBRATA. 



americanus), horse (Equus caballus), ass (Equus asinus), and zebra 

 (Equus zebra). 



ARTIODACTYLA. Two or four toes. Stomach complex ; caecum 

 small, wanting in Hippopotamus. 



Buminants subject their food to a second mastication, bringing 

 it up from the .stomach into which it had passed. They have 

 the " cloven foot " a median pair of hoofed toes, and generally 

 two behind. 



The musk-deer, according to Flower, is a low and doubtful 

 type of Cervidse. It has until recently been placed with Tra- 

 gulus, which is now considered to constitute a distinct family. 

 The musk of commerce is secreted in an abdominal pouch found 

 only in the males. 



Many extinct genera " once linked together the now broken 

 series "of this suborder. 



