Zoological Position. 15 



include the North American Cotton-Tail {Sylvilagus floridanus, 

 Lepus sylvaticus), and the Prairie Hare or Jack-Rabbit {Lepus 

 campestris). ; the European Common Rabbit {Oryctolagus cuni- 

 culus), and Hare {Lepus europceus). The two European species 

 differ in several well marked features, which form the basis of the 

 accepted distinctions between hares and rabbits. The rabbit is 

 distinguished, by its shorter ears and less elongated hind limbs; 

 also by its burrowing habits, and by the , circumstance that the 

 young are born in a blind and naked condition. The hare is more 

 nearly a running or cursorial type, and is distinguished by its longer 

 ears — ^which, moreover, are tipped with black — longer hind limbs 

 and prominent eyes. Unlike the rabbit it does not burrow, but 

 inhabits only an open " form," and the young when born are clothed 

 with hair and able to see. 



The various species constituting this family are distinguished by 

 several features, including the imperfect development of the 

 clavicle, longer ears and limbs, and the presence of a distinct 

 although greatly reduced tail, from the Picas or Tailless Hares' 

 {Ochodontidce) of the mountainous districts of Central Asia, and of 

 North America (Rocky Mountains). The two families are allied, 

 however, in the possession of a common feature, namely, the 

 presence in the upper jaw of a second pair of incisor teeth. This 

 feature distinguishes the sub-order Duplicidentata from that of 

 the Simplicidentata, the latter containing the majority of rodents 

 and embracing all forms with a single pair of upper incisors. 



The mammalian order Rodentia, to which the family belongs, 

 contains a very large assemblage of forms — the Squirrels, Marmots, 

 Cavies, Beavers, Mice, and Porcupines being among the. more 

 familiar. This order is distinguished by the modification of the 

 anterior incisors in both upper and lower jaws to form chisel-like 

 cutting organs, the teeth having their enamel layer disposed 

 chiefly if not wholly on their front surfaces, so that they remain in a 

 permanently sharp condition. This modification is associated with 

 an extensive obliteration of interrnediate teeth, comprising posterior 

 incisors, canines, and anterior premolars; also with elaboration 

 and often great complexity of the remaining premolar and molar 

 teeth, the lower jaw, and, indeed, the^parts of the skull generally. 

 Characteristic of these animals is the extension, both forward and 



