368 HETEROMYS, 
The harsh pelage exhibited in Perognathus and Chetodipus of 
the Pocket Mice, is in the members of HETEROMYs carried farther, 
even to the presence of small flattened spines in the fur. They are 
animals of moderate size, with tails about equaling the head and 
body in length, of various colorations, with a heavier skull, and 
incisors smooth in front. Only one species is found north of the 
Mexican boundary, but a number are natives of Mexico, Central 
America, and the West Indies. They have a rather long, slender 
body, and moderately short legs. 
74. Heteromys. Spiny Pouched Rats. 
= P=: M == vo: 
2} >) 
1 =n 
Heteromys Desm., Nouv. Dict. Hist. Nat. Mamm., 1817, p. 313. 
Type Mus anomalus Thompson. 
Dasynotus Wagl., Nat. Syst. Amphib., 1830, p. 21. 
Saccomys F. Cuv., Mem. Mus. Hist. Nat., Paris, x, 1824 5speeeeas 
Xylomys Merr., Proc. Biol. Soc. Wash., xv, 1902, p. 43. 
Eiomys Merr., Proc. Biol. Soe. Wash:, xv, 1902), per 
Molars rooted; flattened spines mingled with the fur; skull almost 
flat above, slightly arched in middle of superior outline; nasals 
projecting beyond incisors; mastoids level with plane of occiput; 
zygomata depressed, but not dipping to level of palate; occiput 
Fic. 69. HETEROMYS GAUMERI. 
No. 5844 Field Columbian Mus. Coll. Nat. size. 
UPPER TOOTH ROW. LOWER TOOTH ROW. 
Enlarged & times. Enlarged 8 times. 
