456 ORDERS OF MAMMALIA. 



was a contemporary of the Cave-hyaena, Cave-bear, Woolly 

 Rhinoceros, and Mammoth. There can also be no doubt but 

 that the Cave -lion survived into the earlier portion of the 

 human period. 



The only other member of the Felidcz which deserves men- 

 tion, is the "sabre-toothed" Tiger (Machairodus), species of 

 which are known to have existed from the Miocene period up 

 to the Post-Pliocene. In this singular genus the upper canines 

 were greatly elongated, trenchant, and sabre - shaped, with 

 finely-serrated margins. There is no upper true molar, and 

 the praemolars are reduced to two on each side of each jaw. 

 The dental formula is 



.33 I I 22 00 



' 33 ; c 7=1 ; / ; *i=r= 26 - 



Species of Machairodus must have been as large as a Lion ; 

 and the genus is not only European, but is also represented by 

 a form in South America, and another in India. 



CHAPTER XLI. 



ORDERS OF MAMMALIA Continued. 

 RODENTIA, CHEIROPTERA, AND INSECTIVORA. 



ORDER X. RODENTIA. The tenth order of Mammals is that 

 of the Rodents, often spoken of as Glires, comprising the Mice, 

 Rats, Squirrels, Rabbits, Hares, Beavers, &c. 



The Rodentia are characterised by the possession of two 

 long curved incisor teeth in each jaw, separated by a wide in- 

 terval from the molars. The lower jaw never has more than 

 two of these incisors, and the upper jaw very rarely; but some- 

 times there are four upper incisors. There are no canine 

 teeth, and the molars and praemolars are few in number (rarely 

 more than four on each side of the jaw). The feet are usually 

 furnished with five toes each, all of which are armed with claws ; 

 and the hallux, when present, does not differ in form from the 

 other digits. 



The most characteristic point about the Rodents is to be 

 found in the structure of the incisors, which are adapted for 

 continuous gnawing hence the name of Rodentia. The in- 

 cisor teeth are commonly two in each jaw, and they grow from 



