CHIROPTERA 9 



mammals, but rather with the metacarpals or bones of the 

 hand. In the first digit, thumb or pollex, there are two 

 phalanges. Being always partly free from the wing, and 

 armed with a claw, it is used by the animal, when not flying, 

 for purposes of cHmbing, but not, as often stated, in locomotion. 

 In the remaining digits the phalanges are as follows : — 



(The terminal phalanges are often cartilaginous.) 



The modifications in length or development of the digits 

 materially affect the length and strength of the wing and the 

 powers of flight. 



As in other mammals, the hand is attached to a limb 

 consisting of a wrist or carpus with six small bones, a forearm 

 composed of a rudimentary ulna and a long curved radius, and 

 of a humerus or upper arm. These constitute the complete 

 framework of the wing. The length of the forearm is suffi- 

 ciently constant in individuals of the same species to afford in 

 many cases a satisfactory guide to their identification. The 

 humerus is peculiar in the large size of the trochiter and trochin 

 or tuberculum majus and minus. 



The shoulder girdle and sternum are often much modified, 

 especially in the Rhino lophidcs. 



The hind-limb consists of the parts usual in mammals. It 

 is so rotated outwards by attachment to the wing, that the knee 

 points backwards. The foot is armed with claws and used for 

 suspension and progression otherwise than in the air. A 

 remarkable, elongated, cartilaginous process, the calcar, arises 

 from the inner side of the ankle-joint, and helps to support 

 the posterior margin of the interfemoral membrane, or that 

 portion of the wing which occupies the space between the legs 

 and the tail. The points of attachment of the interfemoral 

 membrane to the tail and, especially, to the legs are diagnostic 

 characters, as is also, when present, a lobe which has its point 

 of origin over the calcar, and is known as the post-calcarial 

 lobe. 



B 



