i Cases 
10 & 11 .] 
C2 IJPrEK MAMMAL GALLERY. 
aquatic, and feeding on water-weeds, grass, and other vegetable 
substances. The last three families are restricted to South 
America. 
It may be added that in the true Porcupines {HystrLc) the 
facial portion of the skull (tig. 34) is enormously expanded ; 
while in the Pacas the cheek-arches of the skull are greatly 
inhated and swollen for the purpose of protecting a pouch which 
opens into the mouth. The Oapybara or (]arpincho, in addition 
to its size, is noticeable for the extreme complexity of the last 
molar tooth in each jaw. 
The second suborder of Rodents, Duplicidentata, distinguished 
by possessing two pairs of incisors in the upper jaw, consists 
oidy of the Hares and Rabbits (Lepiis) and the Pikas {Ochotona\ 
Skull of the Hare {Lepus europceus). 
i, incisors ; pm, preinolars ; m, molars. 
animals tar less specialized for gnawing than other Rodents, 
and showing, in some respects, the links by which the order is 
related to other Mammals. Their chief peculiarity is that some 
of the bones of their skulls are singularly imperfect, consisting 
in parts merely of a sort of bony network, especially in the 
neighbourhood of the nose-chamber (fig. 35). They possess 
processes behind the sockets of the eye, very large slits in the 
palate, and united shin-bones. 
Lepus contains many species, all on the whole very much 
alike, of which the three British representatives, the Brown Hare, 
Lepus eiiropjceus ( 860 ), the Alpfne or Blue Hare, L. timidus ( 954 ), 
