1917.] Lang and Chapin, Field Notes on African Chiroptera. 549 



our hand, they were ready to defend themselves with their sharp teeth. 

 But suddenly they might turn, and tails slightly raised, with the help 

 of their folded wings, they would scamper off swiftly on all fours, only to 

 climb quickly into any of the holes or to flatten themselves against the 

 roughened, decayed surfaces of the broken pieces so as hardly to be seen. 



They certainly liked to huddle together in great numbers. Those we 

 kept alive in a box were continually crowding into one corner, squeaking 

 and fighting when separated, until as many as six had settled again over 

 each other. We wondered why those below did not suffocate, yet they 

 seemed to feel no inconvenience. 



The two species show hardly any difference in their behavior. The 

 photograph (Plate LIV) indicates clearly the peculiar molossid way of rest- 

 ing. Instead of hanging by the feet, extended to nearly their full length, as all 

 the fruit bats and long-haired insectivorous bats (e. g., Nycteridse and Rhino- 

 lophidse), these short-haired mastiff-bats never hang free, but cling to the 

 surface with both feet and wings. As they can seldom fly directly into the 

 narrow clefts or hollows where they choose to remain during the day they 

 naturally have to creep on all fours for considerable distances. Since they 

 can crawl forward or backward with the same ease, they can enter or back 

 out of the narrowest fissures without any trouble. At the base of the short 

 first digit all molossid bats show a curious hardened pad that assists in this 

 peculiar manner of progression. These pads are more or less developed in 

 different species, and are to be compared with those of Pipistrellus nanus 

 (p. 530), but never become such specialized organs as the sucker of the 

 South American genus Thyroptera. Those living in the fissures of rocks 

 (e. g., Nyctinomus ansorgei) show naturally much larger pads than those 

 habitually frequenting hollow trees, where the surface is softer, such as 

 Nyctinomus ochraceus, Mops congicus, Choerephon russatus. So used are 

 they to this mode of creeping that, put on the ground they do not even try 

 to flutter off like other bats, but scurry quickly for the darkest spot in sight. 

 When thrown into the air, however, they fly off easily in spite of the sun, 

 making for any bush or tree and creeping quickly under cover. 



When landing on any surface they instantly fold up their wings. The 

 photograph (Plate LIV) reveals well the great assistance they derive from 

 them even in the position of complete rest. As in all other bats, the short 

 first digit of the wing bears a claw, especially sharp in these forms. It can 

 be turned upward, forward, sidewise, and to the rear, in the direction of the 

 other much longer digits that support the flying membranes. Thus they 

 can cling with it to even small roughnesses in any desired position. The 

 toes play an equally interesting role on account of the curious structure of 

 their hairs. All these bats when they finally reach their hiding places cling 



