1898.] NATURAL SCIENCES OF PHILADELPHIA. 329 



bare, with a few very fine scattered hairs. In form the ears are 

 much like those of M. megalotis. Their tips, however, are more 

 abruptly narrowed, a condition made still more apparent by their 

 much smaller size. Inner surface of auricle with eight sharply de- 

 fined cross ridges arising at posterior border and extending about 

 halfway across ear. The distance between the uppermost and lower- 

 most ridge is about 5 mm. 



Feet. — Foot distinctly shorter than calcar and slightly more than 

 half as long as tibia. 



Skull. — In the type the brain case is more elevated immediately 

 behind the orbits, and the zygomata are less flaring than in the 

 skulls of 31. megalotis with which I have compared it, but these 

 differences may prove to be individual. 



Teeth. — When viewed from above, the crowns of the three lower 

 premolars appear to be of approximately equal size, though the 

 second is slightly smaller than either of the others. In 31. mega- 

 lotis the crown of the middle lower premolar is very conspicuously 

 smaller than the first. In other respects the teeth of the two species 

 appear to be identical. 



General remarks. — Micronyeteris microtis is so different from the 

 other described species of the genus that it needs no special com- 

 parison with any. From 31. megalotis its nearest geographical ally, 

 its small ears and uniform wood brown color separate it at a glance. 

 Yet it is probably most closely related to 31. megalotis and 31. hir- 

 suta, since 31. behnii and 31. minuta, the only other known species, 

 are distinguished by differences in the proportions of the parts of 

 the fingers and feet, to say nothing of the peculiar attachment of 

 the wings in 31. minuta. 



In the type of 3Iicro?iycteris microtis the exact form of the nose 

 leaf cannot be determined. The free, upright portion of the leaf, 

 however, appears to be shorter and broader than in either of the 

 races of 31. megalotis. The whole leaf is finely pubescent. 



The striation of the inner side of the ear is very different in 3Iicro- 

 nycteris microtis and 31. megalotis. In the latter, instead of eight 

 sharply defined ridges crowded into the space of 5 mm., there are 

 thirteen ill defined stria? with a distance of nearly 10 mm. between 

 the first and last. 



Micronyeteris megalotis mexicanus subsp. nov. 



Type. — Adult 9 (in alcohol) No. 52,105, United States National 

 Museum (Biological Survey collection). Collected at Plantinar, 

 22 



