MAMMALIA. 7 



incisors chisel-shaped, lower ones pointed: tail round and 

 hairy, shorter than the body. 



1 18. CASTOR. Grinders compound, with flat summits, four on each 

 side above and below : toes of the hinder feet palmated : tail oval, de- 

 pressed, and covered with scales. 



** Clavicles rudimentary. 



19. LEPUS Two subsidiary incisors in the upper jaw 



immediately behind the others : grinders six above and five 

 below on each side, the summits flat, with transverse plates 

 of enamel : inside of the cheeks hairy : ears very large : 

 toes five before and four behind! tail short, and turned 

 up. 



* 20. CAVIA. Grinders compound ; each with one simple and one 

 fork-shaped plate of enamel ; four on each side above and below : toes 

 four before and three behind: tail none. 



ORDER IV. UNGULATA. 



Teeth various: incisors and tusks often wanting in 

 one or both jaws : grinders of one sort : toes large, 

 covered with hoofs. 



* No incisors in the upper jaw ; eight in the lower : 

 two middle toes separate : frontal bones furnished 

 with horns: ruminate. 



*( Horns hollow, growing on a bony core ; persistent. 



* 21. BOS. Horns smooth; directed laterally at first, afterwards re- 

 curved: body thick and heavy: limbs strong: tail moderately long, 

 terminated by a tuft of hair : four inguinal mammae. 



* 22. OVIS. Horns rough and angular; directed backwards and 

 laterally, more or less spirally twisted : chin without a beard : limbs 

 rather slender: tail moderately short: two inguinal mammse. 



* 23. CAPRA. Horns rough and angular; directed upwards and 

 backwards: chin bearded: tail short: mammae two. 



