440 Mr. O. Thomas on a 
9. Molossus bonariensis, Peters. 
?. 62. Asuncion. 16th August, 1900. 
This very distinct species was obtained in some numbers 
by Mr. Perrens at Goya, and Mr. Graham Kerr also caught 
two examples at Waikthlatingmangyalwa, in the Northern 
Chaco. 
Although larger, the skull of M. bonariensis has in general 
shape and the absence of median crests a very considerable 
resemblance to that of Promops nanus, Miller. 
10. Molossus cerastes, sp. n. 
2¢. Villa Rica. 22nd and 26th January. 
29. Sapucay. 9th and 10th June. 
General characters of M. planirostris, but enormously 
larger. 
Size as large as in M. rufus, but the wings proportionally 
shorter. 
Fur of medium length, not so short as in M. planirosiris ; 
hairs of back 3 to 8°5 millim. in length, the longer hairs 
over the shoulders. Fur extending on to base of forearm, 
on to membrane external to terminal half of forearm, and on 
to base of fifth finger above, and on to base of interfemoral 
above and below. Elsewhere the membranes and limbs are 
naked, except for the usual hairs on the toes. Colour 
uniform brown (‘ Prout’s brown,’ or darker) above and 
below *, the hairs not or scarcely paler at their bases. Face, 
ears, and wing-membranes blackish. Lars short, triangular, 
their tips broadly rounded; keel distinct, not flattened 
externally; antitragus as high as long, not overlapping its 
base anteriorly or posteriorly ; tragus triangular. A distinct 
gular sac present in male. 
Skull remarkably broad and flat. Preorbital ridges 
heavily developed, so that the breadth across them is equal 
to that across the brain-case. Cranial crests evident, more 
developed than in planirostris, the sagittal meeting the 
lambdoid crests in a high helmet-like projection. 
Upper incisors large, vertical, parallel, their tips not 
touching each other, and their bases separated from the 
canines. No trace of the small anterior premolar. Lower 
incisors four. Anterior lower premolar three-fourths the 
height of the second, crushed between the latter and the 
canine. 
* The two female specimens, killed in June, are much paler and brighter 
than the two males, Their general tone is almost cinnamon-brown. 
