1894.] NATURAL SCIENCES OF PHILADELPHIA. 235 



XENOMYS {Cont.). HODOMYS (Coiil.). 



Preniaxilla' produced ante- Premaxilhe without wiug-like 



riorly in wing-like exten.^ions extensions, 

 reaching beyond nasals. 



Pterygoid fossa? short- — as Pterygoid fossa^ long — twice 



broad as long. as long as broad. 



Postpalatal notch shorter than Postpalatal notch longer than 



basisphenoid. basisphenoid. 



Basioccipital very narrow. Basioccipital broad. 



Lower molar series curved Lower molar series straight or 



strongly outward anteriorly. nearly straight. 



Only two species of Hodomys are known. Both make extensive 

 inosculating runways among the Agaves and other plants on the 

 brushy side hills where they live. This habit is unknown in the 

 allied genera Xeotoma and Xenomys. Neotoma builds houses or 

 amasses large piles of sticks, cactus spines, or other rubbish ; 

 Xenomys lives in hollow trees ; Hodomys is not known to do either. 



Hodomys alleni (Meiriam). (PI. IX, figs. 1-4; and text fig. 3, a ami d.) 



Xfotonia alleni Merriain, Proc. Biol. Soc. Washington. VII, Sept. 1892, 167-lti9- 

 (Typi- from Manzanillo, Mexico.) 



General characters. — Size large (larger than any known species of 

 Xrotoma) \ ears rather large; tail shorter than head and body, 

 blackish, sparsely haired, the anuulations and scales distinctly visible 

 on both sides. 



Color. — Upper parts from forehead to base of tail deep fulvous or 

 tawny-ferruginous ; nose and sides of face mouse- gray, tinged with 

 bluish in some specimens; under surface whitish, the tips of the hair 

 only being white, the plumbeous basal part showing through ; up- 

 per surfaces of feet whitish, more or less clouded with dusky ; tail 

 blackish all round. 



Cranial characters. — Skull very long and narrow ; angular ; 

 orbital margins of frontals nearly parallel and strongly upturned, 

 with tendency to develop an upturned point opposite middle of 

 orbital fossa; interparietal shield quadrate; nasals produced and 

 pointed anteriorly, truncate or emarginate posteriorly. (Principal 

 characters given under generic diagnosis and not repeated here. ) 



Measurementx of type (taken in flesh). — Total length, 472 mm; 

 tail vertebnt, 225; hind foot, 4(5; ear, 29 (in dry skin). 



