440 PROCEEDINGS OF THE ACADEMY OF [April, 



General Characters. — Similar to M. mexicamis. but smaller, with the 

 dentition more crowded, and the second upper premolar shorter and 

 somewhat weaker. 



Head. — As in M. mexicamis, except that the ears are larger. 



Limbs. — As in M. mexicanus, but rather slenderer, the foot and cal- 

 caneum distinctly weaker. 



Membranes and Fur. — As in M. jnexicanus. 



Color. — This race occurs in two phases, one of which appears to be 

 that of immaturit}'. The dark brown type, which is apparently the 

 immature coloration, is connected by intermediates with the dull 

 rufescent brown type. Brown phase: Above bistre, the hair with the 

 basal half white; base of ears and auricular hairs whitish; below drab, 

 the hair white at the base and tipped with silvery-white ; membranes 

 clove brown. Red phase : Above between chestnut and hazel (Ridg- 

 way's Nomenclature of Colors, pi. iv), the hair light and rather vinaceous 

 basally ; base of ears and auricular hairs of the under color of the upper 

 surface; below dull pinkish vinaceous; membranes between chestnut 

 and liver brown. The intermediate specimens have the upper surface 

 cinnamon rufous, while of this type has the extreme base of the hair 

 smoke-gray, thus making the hair triannulate^ — smoke gray, white and 

 cinnamon rufous. The original series of this race was composed 

 entirely of immature individuals and accordingly all are of the dark 

 brown type. 



Skull. — Very similar to that of M. mexicanus, but distinctly smaller. 

 with the rostrum, for its size, heavier. 



Teeth. — As in il/. mexicanus, but the second upper premolar is with- 

 out the produced anterior shoulder noticed in mexicanus, and the 

 inferior premolars are comparatively shorter and broader. 



Measurements. — Average of five alcoholic topotypes: Total length 

 87.6 mm. (84.5-92); head and body 55.1 (53.5-56.5); head 23 (22.5- 

 23.5); ear 28.5 (27-30.5); greatest width of ear 19.2 (18.5-20.5); tra- 

 gus 9.5 (9-10); forearm 49.2 (48.5-50.5); thumb 12.6 (12-13.2); third 

 digit 83.8 (81-87); tibia 20.2 (19-21); calcaueum 10.6 (10-11.2); foot 

 12.4 (12-13); tail 32.5 (30.5-35.5). 



Average of eleven topotypic and Guadalajara skulls : Total length 23 

 mm. (22.5-23.5) ; greatest zygomatic width 10.8(10.5-11.1) ; intcrorbital 

 width 4 (4-4.2); height at base of second premolar 3.6 (3.3-4); height 

 of brain-case 8.2 (8-9) ; breadth of brain-case above roots of zygomata 

 8.6 (8.3-9) ; width of palatal constriction 2 (2-2.3) ; length of palate 8.6 

 (8.3-9) ; width of palate (including teeth) 7.4 (7-7.8) ; greatest length 

 of mandible 15 (14.6-15.5). 



