THE FAMILIES AND GENERA OF BATS. 17 



the trochiter slightly exceeds the somewhat reduced trochin in actual 

 sizei, while in height it extends conspicuously beyond it as well as 

 beyond the head of the humerus. The double articulation with the 

 scapula is now complete, and the surface on which the flangelike 

 trochiter acts is nearly as large as the glenoid fossa. The shaft of the 

 humerus is nearly straight, or with a moderate single curvature ; dis- 

 tal extremity scarcely wider than shaft, the articular surface not 

 displaced outward, the short epitrochlea scarcely more than the base 

 to the high spinous process, which projects beyond distal extremity in 

 much the same manner as the trochiter beyond head." 



PHALANGES. 



The first digit contains two phalanges, the distal- of which bears a 

 claw, functional in all bats except the two genera of Furipteridae, 



In the second digit the metacarpal alone is present in the Embal- 

 lonuridse, Nycteridse, Rhinolophidae, Hipposideridae, Natalidae, Fu- 

 ripteridae, and Thyropteridae. One distinct bony phalanx is present 

 in all other families of Microchiroptera except the Rhinopomidae, in 

 which there are two. Three phalanges are present in this finger in 

 all of the Megachiroptera, the terminal bone in most genera provided 

 with a claw. 



Three is the usual number of phalanges in the third, fourth, and 

 fifth digits. The distal phalanx is always cartilaginous in the fourth 

 and fifth, though in carefully prepared material its joint with the 

 second phalanx may be detected when both are present. 



In the third digit the terminal phalanx is ossified in the Phyllosr 

 tomidse, Desmodontidae, Thyropteridse, Myzopodidse, and Mystaco- 

 pidae. When not completely ossified its joint with the second phalanx 

 is at least clearly indicated and partially of bone, a condition readily 

 observed in the Vespertilionidae and Molossidse. No distinct third 

 phalanx is present in the third, fourth, and fifth fingers of any 

 Megachiroptera, or among the Rhinopomidae, Emballonuridse, Noc- 

 tilionidse, Nycteridse, Megadermidae, Rhinolophidae, Hipposideridae, 

 Natalidse, and Furipteridae, though it is probable that the terminal 

 cartilage, when present, usually, if not always, represents this bone. 



Sternum and Shoulder Girdle. 



The general characteristics of the sternum and shoulder girdle 

 (Plate. XI, fig. 1; Plate XII, fig. 3; Plate XIII, fig. 2; Plate XIV, 

 fig. 1) are as follows: 



Sternum. — The presternum is large, strongly keeled, and with three 

 anterior lobes, one of which is vertical and continuous with the keel 

 (from which it is often scarcely to be distinguished), the two others 



a In the genus Eptesicus both processes are unusually short. 

 25733— No. 57—07 m 2 



