1902.] NATURAL SCIENCES OF PHILADELPHIA. 395 



JRemarks. — Although Nyctmomojjs yueatanicus is iu many respects 

 intermetliate between the small N. europs and the larger N. lati- 

 caiidatus and N. femorosaccus, it is a very distinct species. Its 

 relationships are evidently with the larger forms, though super- 

 ficially it bears a close resemblance to N. europs. 



Mr, Nelson and Mr. Goldman secured the specimens in crevices 

 of the ruins at Chichen, Kza. A bat which they supposed to be 

 the same was seen at Tunkas and ]Merida. 

 Molossus nigricans sp. nov. 



Type.— Adult male (skin and skull), No. 90,941, United States 

 National Museum (Biological Survey collection). Collected at 

 Acaponeta, Tepic, Mexico, August 2, 1897, by E. W. Nelson and 

 E. A. Goldman. Original number, 11,433. 



Characters. — Slightly larger than 3Iolossus rufus from Paraguay; 

 color blackish-brown, the shoulders frequently though not invari- 

 ably grayish. Red phase uncommon, brighter than that of J/. 

 rufus, but apparently less so than iu M. pretiosus. 



Color. — Type: Upper parts a uniform very dark seal-brown, 

 interrupted on shoulders by a crescentic area of broccoli-brown 

 about 10 ram, in width. This lighter color appears again as an 

 ill-defined wash on head between ears. Under parts like back, 

 but everywhere lightened by a wash of broccoli- brown, this most 

 conspicuous on Ihi'oat. Eai-s and membranes an indefinite blackish- 

 brown. Red phase: The few specimens in the red phase have 

 been immersed in alcohol for ten years and are therefore not to be 

 trusted as regards color. They are now a uniform tawny, ratlier 

 less bright than M. 2}retiosus in the same pelage. 



Variation in color, as shown by the skins iu the dark phase, is 

 slight, and such as occurs is mostly a mere darkening of the general 

 tint and the partial or complete obliteration of the shoulder cres- 

 cent. In the majority of specimens, indeed, this crescent is absent. 



Skull and Teeth. — The skull is about the same size as that of 

 Molossus rufus, but the rostrum is heavier and the interpterygoid 

 space and the palate are wider. On the other hand, the sagittal 

 and lambdoid crests appear never to reach the extreme development 

 seen in Molossus rufus. 



Teeth as in Molossus rufus, but distinctly heavier throughout. 



Measurements. — External measurements of type: Total length, 

 145; tail, 53; tibia, l.S.H; foot, 12 (11); forearm, 52.(5; thumb, 



