1300 



THE RODENTS 



representative of a distinct family, but there can be little doubt that it is merely a 

 highly-specialized member of the present group. The African crested rat (Lophio- 

 mys imhausi) derives its name from the great crest of long, erectile hairs running 

 down the back and tail, some of which are as much as three and one-half inches in 

 length, and at their bases have a peculiar spongy structure. The tail is long and 

 bushy, the limbs short, and the ears small. In the hind-foot the small front toe can 

 be opposed to the others. The general color is blackish brown, but there is a large 

 triangular white spot on the front of the head, and a white streak beneath each eye, 

 while the tip of the tail is also of the same hue. Moreover, the long hairs of the 

 body have only the middle portion dark colored, their two extremities being white. 

 Internally, the crested rat differs from all other members of the family by its rudi- 

 mentary collar bones, and also by the circumstance that the sides of the hinder part 

 of the skull are completely roofed over with bone, as in a turtle. This Rodent in- 

 habits the district of Shoa, and is doubtless arboreal, although nothing definite is 

 known of its habits in a wild state. 



THE VOLES 

 Genus Microtus * 



The voles, together with their near allies the lemmings and the musquash, con- 

 stitute a group closely allied to the Cricetines, but distinguished by the peculiar 

 characteristics of their molar teeth. Indeed, the voles and their allies are evidently 



nothing more than a specialized modification of the Crice- 

 tine type, and it is more as a matter of convenience than 

 from any well-founded distinctive characteristics that they 

 are placed by themselves in a distinct subfamily. The 

 whole group is characterized by the molar teeth being 

 usually rootless or with imperfect roots, and composed of 

 two longitudinal rows of alternately-arranged triangular 

 prisms. These prisms, as shown in the accompanying 

 figure, decrease in number from the first to the third 

 tooth in each jaw, but are variable in number in the 

 > <3|^> different species, and thus form a valuable aid in their 



(^^> discrimination. The tail of the voles is either short or of 

 moderate length, and these Rodents are distinguished 

 from the true rats and mice not only by this characteristic 

 but likewise by their more corpulent form, their smaller eyes 

 and ears, their more obtuse muzzles, and proportionately- 

 shorter limbs. The subfamily has a wide distribution 

 in the Northern Hemisphere, but is quite unknown in Asia 



south of the Himalayas, in the Malayan region, and in Africa and South America. 

 It is connected with the Cricetine subfamily by a North- American genus known as 

 Phenacomys, in which the molar teeth are furnished with roots. 



"The name Arvitola has been commonly applied to the voles, but by the rules of zoological nomenclature it 

 has had to give place tc Microtus. 



CROWN SURFACE OF THE 

 UPPER AND I, O W E R 

 MOI.AR TEETH OF THE 

 CHINESE VOI,E. 



(From Thomas.) 



