GROO VED- TOO THED MICE AFRICA N CRES TED RA T 1 299 



THE GROOVED-TOOTHED MICE 

 Genera Rhithrodontomys and Rhithrodon 



Two groups of American Cricetines are distinguished by their upper incisor 

 teeth being marked by parallel grooves. Of these, the American harvest mouse 

 {Rhithrodontomys humilis) resembles the rice-field mouse in external appearance, and 

 is found in the southern part of the United States as far north as Iowa; the other 

 two species of the genus being also North American. 



The Rhithrodonts, on the other hand, are exclusively South American, and are 

 characterized by their rabbit-like appearance, the head being very short, with a 

 highly-convex profile, very large eyes, and rather large, rounded ears. The rabbit- 

 like rhithrodon {Rhithrodon cuniculoides] , from Patagonia, is one of the best-known 

 species. The length of the head and body is six and one-half inches, and that of . 

 the tail about half as much again. Its general color is yellowish gray mixed with 

 black, with the under parts pale yellow, and the rump, feet, and lower surface of 

 the tail white. 



THE WOOD RATS 



The Florida rat {Neotoma floridana) is the best-known representative of a small 

 genus of North- American Cricetines, distinguished by their large size and the circum- 

 stance that the cusps on their molars show some approximation to the type of struc- 

 ture obtaining in the voles. The Florida rat, which inhabits the southern part of the 

 United States and the north of Mexico, is about the size of an ordinary rat, to which 

 it also approximates in general coloration, although the under parts and feet are en- 

 tirely white. This species has a thin, scaly tail, but in the bushy -tailed wood rat 

 {N. cinerea] from the northwestern and western districts of North America, this ap- 

 pendage resembles that of a dormouse. The wood rats are active, climbing animals, 

 sometimes found in forests, but in other cases inhabiting rocky districts. In woods 

 or near streams they frequently make heaps of twigs, straw, etc., in which to form 

 their nests. The young, of which there are from three to six in a litter, cling to the 

 sides and back of the female parent when she is walking about, somewhat after the 

 manner of certain opossums, and two litters are generally produced in the year. In 

 addition to vegetable food, the Florida rat will also eat crawfish and frogs. 



There are several other genera belonging to the Cricetine subfamily 



which cannot be mentioned here. It may be observed, however, that 

 Cricetines 



Hypogeomys, together with four other genera, are confined to Mada- 

 gascar, where they are the sole representatives of the Rodents. 



THE AFRICAN CRESTED RAT 

 Genus Lophiomys 



A rare and remarkable Rodent from Northeast Africa differs from the preceding 

 Cricetines in certain features, which have been regarded as entitling it to rank as the 



