CHAPTER XXXIV 



RODENTS concluded 



THE HARE-LIKE RODENTS 



Families LAGOMTID^ and 



THE whole of the Rodents described in the preceding chapters are characterized 

 by having but a single pair of incisor teeth in the upper (as in the lower) jaw; and 

 they are hence collectively spoken of as the single-toothed Rodents, or Rodentia 

 Simplicidentata. On the other hand, the hares and rabbits, together with their 

 cousins the picas, have a second smaller pair of incisors placed behind the large 

 front pair in the upper jaw, as shown in the accompanying cut. These Rodents are 



accordingly regarded as constituting 

 a group of equal value with the one 

 containing all the other families, for 

 which the term double-toothed Ro- 

 dents, or Rodentia Duplicidenta, is 

 adopted. In the young of this 

 group three pairs of incisors are 

 present in the upper jaw, but the 

 hindmost pair soon disappear, and 

 are not succeeded by permanent 

 teeth. In addition to these extra 

 incisor teeth, these Rodents are 



characterized by the enamel extending all round the large incisors, instead of being 

 confined to their front surfaces. In the skull the palate is distinguished by the 

 shortness of its bony portion, in which there are very large vacuities in front; while 

 its hinder border is situated between, instead of behind, the molar teeth. In all 

 cases the latter teeth have tall crowns without roots, and are divided into parallel 

 transverse plates surrounded by enamel. In the hind-limb the bones of the lower 

 leg (tibia and fibula) are united. The upper lip is invariably cleft. 



These Rodents, which are divided into two families, are all strictly terrestrial in 

 their habits, and have a wide geographical distribution, although more abundant in 

 the Northern than in the Southern Hemisphere. 

 (1360) 



SKELETON AND TEETH OF HARE. 



