238 



ZOOLOGY. 



ivhicli has but one digit or toe and walks on its single toe- 

 nail. 



Mammals have larger brains, and a more roomy brain- 

 cavity in the skull than any of the lower animals, while 

 the teeth are of four kinds, i.e., molars, premolars, canines, 

 and incisors. 



Many mammals, especially those that chew the cud, as the 

 leer, ox, rhinoceros, etc.,ai-e armed with horns. There are 

 two kinds of horns — those with a bony coi'e surrounded with 

 a horny case of skin as in the deer; while in others, as the 

 antelopes, sheep, goats, and oxen, the horns are hollow. 



Fig. 281.— Teeth of a Mammal. The incisors are placed in front of the large 

 conical canine teeth; 2, 3, premolars; in. 1-4, four molar teeth. 



In most horned mammals the horns are not shed; in the 

 deer they drop off every year; in the prong-horned ante- 

 lope the horns are also shed yearly. 



It is a rule that the males of such animals as are provided 

 witli tusks or horns always fight for the possession of the 

 female. It is so with bulls, deer, elephants, boars, and 

 ram,'^; at the same time these are organs of defence by 

 which the males jirotect their family, flock, or lierd. On 

 the other hand, in the female rhinoceros, some antelopes, 

 the reindeer, as o])i)oscd to tlie other deer, some sheep and 

 goats, etc., the horns are nearly as well developed as in the 

 0|iposile sex. The modes of atlack are various: the ram 

 charges and butts with the base of his horns, the domestic 



