Vol. VII, pp. 159-174 September 29, 1 892 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTION OF A NP^W GENUS AND SPECIES OF 



MUPvINE RODENT (XEXOMYS NELSOXI) 



FROM THE STATE OF COLUVIA, 



WESTEPvN MEXICO. 



BY ('. HART :\ierria:\i, .M. I). 



Among the man}' interesting mammals recentl}' collected by 

 "Sir. E. W. Nelson in western Mexico is a handsome rat-like 

 rodent which seems to be not only an undescrilied species, but 

 the type of a new genus. In form and general external appear- 

 ance it looks like a rather small wood rat of the genus Neotmna, 

 but differs from the members of that genus, and in tact from all 

 other known North American murines, in having a large and 

 clearly defined whitisli spot over each eye and another (though 

 less conspicuous) below each ear." The upper lii)s and cheeks 

 also are white more than half way to the eyes, giving the animal 

 a very prett}^ as well as unusual physiognomy. The color of 

 the back and up})er parts generally is deep tawnj^ red or fulvous, 

 while the under parts are creamy Avhite. The skull and teeth 

 present a combination of characters so unlike those of any known 

 rodent that a new genus must be framed for its reception. While 

 resembling Neotonm more closely than any other genus, it differs 

 from it in many important characters. With a skull mucli 

 like that of Nentomd, mexicnmi, it has well developed supraorl)ital 



■.^•2-Ri(ii,. Soc. W.^sii., Vol,. Vir, 1S<I2. (159) 



