INTKODrCTION. XIU 



form is much larger than in Megachiroptera. On the dorsal aspect 

 of the wrist, in Phyllostoma hastatum, there are three weU-developed 

 sesamoid bones — one on the radial side, protecting the radiocarpal 

 joint internally, another covers the metacarpo-carpal joint of the 

 thumb, while the third and largest overlies the articulation of the 

 OS magnum with the second and third metacarpal bones. 



The manus is, in all the species, composed of five digits. The 

 first, fourth, and fifth respectively consist of a metacarpal bone and 

 two phalanges ; in the second and third the number of phalanges is 

 different in certain families. 



The first finger (or thumb) always terminates in a claw, which, 

 with the prosdmal phalanx, is most developed in Megachiroptera* 

 and in the frugivorous species of PhyllostomidoB. The second finger 

 reaches its highest development in Megachiroptera, consisting of a 

 metacarpal bone and three phalanges, the terminal phalanx being 

 provided with a claw (except in Eonycteris, Notopteris, and Cepha- 

 lotes). In these three genera (which include only a single species 

 each) the third phalanx is short but quite distinct, and is included 

 in the wing-membrane. In nearly all the species of Microchiroptera, 

 on the other hand, there is a single rudimentary phalanx only in the 

 second finger ; and in Rhinqpoma microphyllum alone are two pha- 

 langes found. The presence, therefore, of three phalanges in the 

 middle finger is characteristic of the Megachiroptera t. In thei?Ai- 

 nolophidce there is no distinct phalanx in the second finger ; a slight 

 thickening like a joint terminates the osseous portion of the meta- 

 carpal bone, but I have not been able to distinguish a true articular 

 surface. In the Nycteridce, Vespertilionidce (except Thyroptera), and 

 Phyllostomidce there is a short but generally distinct phalanx ; in 

 Thyroptera (in other respects also a most anomalous genus, vide 

 infra, p. xiv) the second fijiger is represented by a rudimentary meta- 

 carpal bone only. In the JEmballonuridce, especially in the genera 

 in which the first phalanx of the third finger is folded (in repose) 

 forward upon the upper surface of the metacarpal bone, the second 

 finger is formed by the metacarpal alone ; in Noctilio (which so 



* The species of ttiis Suborder, when feeding, grasp the fruit between the 

 claws of the thumb and second finger. These fingers ai-e, to a certain extent, 

 opposable in these Bats, and this is evidently rendered possible by the different 

 form and mode of articulation of the trapezium and trapezoid bones, compared 

 with the same parts in Microchiroptera. 



t This character has been accidentally omitted from my definitions of the 

 Suborders at p. 2. 



