THE MASTIFF-BATS 297 



flat feet, and the freedom' of their feet from the wing membranes, the mastiff -bats 

 and their allies are more adapted for crawling on the ground than any other mem- 

 bers of this group of animals. And the result of observations on living specimens 

 has been to confirm these inductions, made upon the evidence of structural 

 peculiarities. 



The mastiff-bats are an American group, found in the tropical and subtropical 

 regions of both divisions of the Western Hemisphere. With the exception of two 

 species, in which the number of the lower incisor teeth is reduced to a single pair, 

 they have either 26 or 28 teeth, of which \ on either side are incisors, while the 

 cheek-teeth number either or . The upper incisors are placed close together in 

 the middle line ; and the large ears, which have a small tragus (occasionally absent) 

 are united by their inner margins. In common with two nearly allied genera of 

 bats, they have very capacious lips, which in most of the species are thrown into a 

 number of wrinkles or puckers ; and they are further characterized by their long 

 and slender wings. The great length and narrowness of the wings indicate, as 

 Dr. Dobson observes, rapid flight ; and since they also possess the power of vary- 

 ing the length of the membrane between the legs by a "reefing" process, they 

 must have great dexterity in suddenly changing their direction, as when they 

 are compelled to double in pursuing swiftly flying insects ; and, again, their ex- 

 pansive and capacious lips aid the teeth in seizing and retaining the round and 

 solidly-armored bodies of the larger beetles ; so that it would seem that they are 

 better adapted than any other members of the order for capturing insects of very 

 swift flight. 



Of the red mastiff-bat (Molossus rufus) an account is given by Mr. P. H. 

 Gosse, from which it appears that this bat inhabits the roofs of houses and the 

 hollow trunks of palm trees, where colonies of large size may sometimes be found. 

 It is more active when on the ground than any other species ; and, indeed, on such 

 occasions its motions are so rapid that some dexterity is required to ensure its cap- 

 ture. In the act of running it rests on its wrists, with the fore part of the body 

 considerably raised. In the hollow stem of a palm tree, examined by another 

 observer, it was found that while in one place the males of this species were col- 

 lected together to a number approaching two hundred, in another spot the assem- 

 blage consisted almost entirely of females, with only a solitary male among them 

 here and there. This distinction of the resting places of the two sexes has also been 

 noticed in certain other bats. 



In describing the habits of another species, the chestnut mastiff-bat (M. 

 glautinus}, Mr. Gosse writes that "soon after sunset we hear the scrambling of 

 little claws along the plaster (in the loft above) gradually tending towards the point 

 where the holes under the eaves is situated. ... I judge that they crawl 

 along one after another in a straight line to the outlet, in parties. The family 

 assured me that after the mastiff-bats had emerged a few hours, they invariably 

 returned into the hole again ; and they several times directed my attention to them 

 when returning. They return between eight and nine o'clock, and issue forth 

 again before the morning twilight. W T hen handled, its impatience of confinement 

 is manifested by a continuous screeching, not very loud, but exceedingly harsh and 



