248 bulletin: museum of comparative zoology. 



the two species, and one that has not apparently been noticed hitherto, 

 is that in obscurus there are on the posterior border of the femora, 

 more particularly at the distal ends, some half dozen long hairs that 

 project stiffly out nearly a centimeter beyond the short close fur. 

 These hairs, though present in crassicaudatus, are much shorter, and 

 less stiff, so that when wet in alcohol they lie flat with the fur of the 

 body instead of projecting boldly. 



Various authors have recorded Molossus obscurus from the West 

 Indies; but in the absence of specimens on which these records are 

 based, it is difficult to determine which of the two species is meant. 

 This difficulty is increased by the fact that the West Indian represen- 

 tative of M. obscurus is slightly but constantly smaller than typical 

 specimens from the mainland (the type locality is probably Surinam 

 or Cayenne). This fact I pointed out previously (1908, p. 58), but 

 at that time had only four specimens from the Lesser Antilles. Since 

 then Dr. Thomas Barbour has presented to the Museum five alcoholic 

 Molossi from Jamaica, collected by him at Mandeville in 1909. A* 

 comparison of these nine Antillean bats with a series of M. obscurus 

 in the Museum collection from northeastern Brazil shows that the 

 latter are larger and heavier-bodied, with larger skulls, teeth, and 

 forearms. The specimens from Jamaica seem identical in every way 

 with alcoholics from Dominica and Sta. Lucia. If this slight amount 

 of difference be considered a sufficient basis for separating the Antillean 

 Dusky Bat, the name Molossus fuliginosus of Gray, 1838, shown by 

 Dobson (1878, p. 413) to be based on Jamaican specimens, would be 

 available for it, except that this name is unfortunately preoccupied by 

 Molossus fuliginosus of Cooper, 1837, for Nyctinomus cynocephalus 

 of South Carolina. Recently, however, Dr. J. A. Allen has described 

 as Molossus verrilli a skin and skull from Samana, San Domingo, 

 which he compares with the much smaller M. tropidorhynchus of Cuba, 

 than which it is said to be much larger and " general coloration darker." 

 The measurements given are: forearm, 40 mm.; third metacarpal, 

 41; skull, total length, 17; width of brain case, 9. 



The measurements of a specimen of Molossus (M. C. Z., No. 7382) 

 from Mandeville, Jamaica, are given below, and in parentheses after 

 each the corresponding dimensions of M. obscurus from Brazil (M. C. 

 Z., No. 3063): — total length, 94 mm. (104 mm.); tail, 36 (40); hind 

 foot, 8 (9); ear from meatus, 10 (15); tibia, 12 (14); forearm, 38.5 (43). 

 Skull, greatest length, 17 (19); basal length, 12.4 (15); palatal 

 length, 5.7 (7); zygomatic breadth, 10.8 (11.2); interorbital con- 

 striction, 4 (4); upper tooth row, excluding incisors, 6.4 (6.7); lower 



