252 CHIEOPTERA. 



testes abdominal or inguinal ; the mammary glands thoracic, and 

 generally post-axillary ; the uterus simple or two-horned ; the pla- 

 centa discoidal and deciduate ; and the smooth cerebral hemispheres 

 do not extend backwards over the cerebellum. The dental series 

 consists of four kinds of teeth : incisors, canines, premolars, and 

 molars; and the dental formula never exceeds i. ^, c. j^, pm. ^' 

 m. 3i^,= 3S teeth (Dobson). 



Besides the "wing-membrane" and " interfemoral membrane," 

 there is a smaller membrane in front of the humerus and forearm 

 called the •■ antebrachial membrane.'' The relative position of the 

 different membranes, and of the bones supporting the wing-mem- 

 brane, is shown in the accompanying woodcut (fig. ~2). The 

 manus or hand is always composed of five digits ; of these the first 

 (or thumb), fourth, and fifth consist each of a metacarpal and two 

 osseous phalanges, in the second and third the number of phalanges 

 varies slightly. The first digit or thmnb is partly free from the 

 wiug and always terminates in a claw. The hind limb is but 

 poorly developed. 



Few, if any, animals have so dehcate a sense of touch as bats. 

 In 8pallanzani"s experiments, bats deprived of the power of seeing, 

 hearing, or smeUing, liew through a room, carefully avoiding the 

 numerous threads that were stretched across it. This sense of 

 touch, so acute as to feel the slightest movements of the air, is 

 probably chiefly exercised by the wing-membrane, the gi-eatly deve- 

 loped ear-couch, and, in the leaf-nosed bats, by peculiarly formed 

 expansions of integument around the nostrils. In several families 

 of insectivorous bats, a process called the tragus arises inside the 

 inner or anterior margin of the ear (fig. 73), whilst a lobe at the 

 base of the outer margin opposite the tragus, and known as the 

 antitragus, is sometimes of considerable dimensions. The ears are 

 extremely mobile. 



Bats vary in their powers of flight almost as greatly as birds do, 



Fig. 73. — Ear of Ve^periigo abramus. 

 a.m., outer margin ; i.rn., inner margin ; t., tragus ; a.t., antitragus. 



those with long narrow wings being much swifter than the short- 

 winged forms. The species of stronger flight appear, as a rule, 

 earlier in the evening, even in some cases before sunset, and may 

 often be seen hawking insects in company with swallows and 



