MURIDvE. 393 



Family MURIDJE. 



This large and cosmopolitan family comprises the mice and rats, 

 with a large number of allied forms. The following are the 

 principal characters : 



Skull without postorbital processes. Infraorbital opening large, 

 almost always wide above, and terminating below in a narrow 

 groove, the outer wall of which is always a flattened plate, forming 

 the lower root of the maxillary zygomatic process. Malar short 

 and slender. Premolars none ; dentition in all Indian genera 



3 3 



The number of subfamilies into which this family was divided 

 by Peters and Alston (P. Z. S. 1876, pp. 69, 80), who have been 

 followed by several writers, appears to me too large, and I cannot 

 agree in placing Nesocia, which is barely distinguishable generically 

 from Mus, in a distinct subfamily from the latter. At the same 

 time, the classification of this extensive family is very difficult. 

 The Indian forms may be thus classed, but the distinctive characters 

 do not always apply to genera not found in India : 



A. Tail much more than ^ total length, 



generally | or more. 



a. Crowns of worn molars with oblique 



subparallel bands of enamel ; tail with 



long coarse hair .................. Platacanthomyince. 



b. Crowns of worn molars with transverse 



laminse forming oval or lozenge-shaped 

 patterns ; tail hairy ; hind legs elon- 

 gate .......................... Gerbillince. 



c. Crowns of upper molars with 3 longi- 



tudinal rows of tubercles, lower with 

 2 rows (except in Hapalomys) ; worn 

 molars with transverse enamel-bands 

 curved or straight ; tail naked or 

 thinly clad, scaly ................ Murince. 



B. Tail (in all Indian forms) less than % total 



length ; all molars either with tubercles 

 in 2 longitudinal rows, or composed of 

 subtrigonal prisms similarly arranged. . Cricetina. 



As with other small mammals, the measurements are chiefly from 

 specimens preserved in alchohol, and in these, especially if strong 

 spirit has been used, the body contracts in length rather more than 

 the tail, whilst membranous parts, such as the ears, shrink rather 

 more in proportion than the body. 



