ZOOLOGICAL posrnoN 7 



tailed Jack Rabbit (Lepus campestris). In recent decades, European 

 hares have been several times introduced and liberated in North 

 America, and are now established in certain parts of the Eastern 

 United States and in Ontario, Canada. The two common European 

 species differ in several well-marked features which form the 

 basis of the recognized 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 for a time after birth are blind and naked. The 

 hair is more nearly a running or coursing type, and is distinguished 

 by longer ears, which are, moreover, tipped with black, longer 

 hind limbs, and prominent eyes. It inhabits an open "form" 

 and the young directly after birth are clothed with hair and able 

 to see. Upwards of one hundred species of Leporidae have been 

 described in North America. They are variously known as hares 

 or rabbits. It is generally considered that the American forms, 

 aside from two aberrant genera, are hares, but in form and habits 

 the Varying and Prairie Hares of the genus Lepus conform more 

 closely to the type of the European Hare, while the Cotton-tails, 

 members of the genus Sylvilagus, make at least some approxi- 

 mation to the European Rabbit. 



The various species constituting this family are distinguished 

 from the Picas or Tailless Hares {Ochotonidae) of the mountainous 

 districts of Central Asia and of North America (Rocky Mountains), 

 by several features, including the imperfect development of the 

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

 though greatly reduced tail. 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 dis- 

 tinguishes what was formerly described as the suborder Duplici- 

 dentata from the suborder Simplicidentata, the latter containing 

 the majority of rodents and embracing all forms with a single pair 

 of upper incisors. 



Authorities now tend to designate the Duplicidentata, to which 

 the family Leporidae belongs, as the mammalian order Lagomorpha 

 and to restrict the order Rodentia, which was formerly considered 

 to include both the above suborders, to the larger assemblage of 

 mammals with only one pair of upper incisors, such as squirrels. 



