364 



ANATOMY OF VERTEBRATES. 



§ 181. Skeleton of Rodentia. — A. Vertebral Column, — The Ro- 

 dentia have seven cer^dcal, and, as a rule, nineteen dorso4umbar 

 vertebrae. The agile Hares with flexile trunk have long loins, 

 viz. D 12, L 7, fig. 229. The Jerboas, fig. 232, that bear the 



Hare (Lepus timidus). 



trunk aloft, like the Kangaroos, have also twelve dorsal and 

 seven lumbar vertebrae : the burrowing Porcupines and SAvim- 

 ming Beavers, fig. 230, have their trunk braced by a greater 



230 



Beaver {Castor Fiber). 



number of long moveable ribs, making in Castor 

 Fiber, D 15, L 4 ; in Hystrix cristata, D 15, L 4 ; 

 in Hystrix alopha, D 14, L 5. The average Rodent 

 number is D 13, L 6. Exceptions are few, and 

 fewer than at first sight, if well looked to ; thus, a 



