146 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



Measurements. Total length, 180: tail vertebrae, 113; hind 

 foot, 21. Skull much broken; lengjth from alveolus of incisors to 

 posterior end of palate, 9; length of palate, 5; length of nasals, 9; 

 least interorbital width, 3; length of upper tooth row, 4. 



I compared this specimen with Dr. Merriam's numerous 

 types and the extensive series in the Biological Survey collection, 

 but it differed from them all save one. This was an example 

 from Patzcuaro, the type locality, which had probably been over- 

 looked and had not been named. 



Rhithrodontomys g. helvolus. Merr. Proc. Biol. Soc. Wash.. 

 1901, p. 554. 



One specimen from Ocotlan, State of Jalisco. 



GENUS HETEROMYS. 

 Heteromys. Desm. Mamm. , 1822, p. 313. 



SUSGENUS LIOMYS. 



Liomys. Merr. Proc. Biol. Soc. Wash., 1902, p. 44. 



Heteromys alleni. Coues. Bull. Mus. Comp. Zool. 1881. viii, p. 



187. 



One specimen from Patzcuaro. 



This specimen represents the typical style from Hacienda 

 Angostura, State of San Luis Potosi. It is a dark animal with 

 the central dorsal region slightly darker than the rest, but with- 

 out any distinct saddle. 



Heteromys albo-limbatus. Gray, Proc. Zool. Soc. , 1868, p. 205. 



Two examples; one from Patzcuaro, State of Michoacan, and 

 one from Puenta de Ixtla, State of Morelos. 



This species, while resembling /f. alleni \\\ its general appear- 

 ance, is rather lighter in color and with a very distinct saddle. 



Heteromys *exiguus. Sp. nov. 



One specimen. 



Type locality. Puenta de Ixtla, State of Morelos. 



Gen. char. Size small; no lateral line: well marked saddle. 



Color. Above mixed buff, brownish black and dark gray 

 forming a well marked dark saddle on middle of back; sides of 

 head, neck and body, with rump and thighs, light gray: lips, 

 under parts and hands white; arms, legs and feet yellowish white; 

 no lateral line; tail above blackish brown, beneath white. 



*Exiguus, a. urn-, small in size. 



