CHIROPTERA. 645 



nearly equals that of the head and body. Its form is very diverse. In 

 many species the tragus is greatly developed, and in the Rhinolophidae, 

 in which the tragus is absent, compensation is probably afforded by the 

 large bullae osseae and the largely developed nose-leaf. 



The patagium consists of (1) the antebrachial portion which extends 

 from the point of the shoulder along the humerus and more or less of the 

 fore-arm to the base of the thumb, the metacarpal bone of which is partly 

 or wholly included in it, (2) the wing-membrane which is spread out 

 between the greatly elongated fingers, and extends along the sides of the 

 body to the posterior limbs, generally reaching to the feet, and (3) the 

 interfemoral membrane which is the most variable part and is supported 

 between the extremity of the body, the legs and the calcar. In most 

 species the wing-membrane arises from the sides of the body, but in a 

 few (Notopteris, Cephalotes, etc.) it springs from the middle line of the 

 back. The interfemoral membrane is best developed in the insectivorous 

 forms, and aids them in their rapid doubling movements. In the frugi- 

 vorous and blood-sucking species it is deeply cut out behind or forms a 

 narrow projection along the legs. 



Odoriferous glands and pouches opening on the surface of the skin are 

 present in many species. The chief of them are the frontal pouches of 

 Phyllorhina, the gular glands and pouches of Taphozous, Molossus, Phyl- 

 lostoma, etc., the shoulder glands and pouches of Pteropus, etc., the pubic 

 and anal glands of Rhinolophidae, etc., and the wing-pouches of 

 Saccopteryx. 



Skeleton. In addition to the points already noted, the following fea- 

 tures may be mentioned. The vertebral column is short and constant 

 in form. There are usually 12 thoracic and 5 lumbar vertebrae. With 

 the exception of the axis none of the cervical or thoracic vertebrae develop 

 spines. From the first thoracic to the last lumbar vertebra the spinal 

 column forms a single curve backwards. 



The skull is the most variable part of the skeleton. The postorbita 1 

 processes of the frontal are absent or short in Microchiroptera, long and 

 traversed by a foramen in Megachiroptera, and in Pteropus leucopterus 

 the orbital ring is complete. The premaxillae are very variable, and 

 may be cartilaginous or almost absent. The zygomatic arches may be 

 strong, slender or absent. The tympanic bullae are without an external 

 canal, and are loosely connected with the adjacent bones. 



The clavicle is always well developed, and the spine of the scapula has 

 a large acromion. The humerus has a large pectoral ridge, and is without 

 a supracondylar foramen. The ulna is small and ankylosed with the 

 radius. In the carpus the scaphoid, lunar and cuneiform are ankylosed 

 to form a single bone and the distal bones are normal. The pollex always 

 has a claw, as has the second digit in most Megachiroptera. The first, 

 fourth and fifth digits possess two phalanges ; in the second and third 

 the number of phalanges varies. In Megachiroptera the second digit 

 has three phalanges ; in most Microchiroptera it only has a single rudi- 

 mentary phalanx (absent in the Rhinolophidae). The third finger is the 

 longest, and except in the Phyllostomidae and one or two others in 

 which it has three, bears two phalanges only. The metacarpals and 

 phalanges of the second to the fifth digits are for the most part elongated. 

 The pelvic girdle is weak. The fibula is reduced except in the Molossinae. 



Dentition. The molar teeth of the insectivorous forms are acutely 

 tubercular, with usually well-developed W-shaped cusps. In the frugi- 



