THE FAMILIES AND GENERA OF BATS. 
17 
the trochiter slightly exceeds the somewhat reduced trochin in actual 
size*, 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 Furipteridse. 
In the second digit the metacarpal alone is present in the Embal- 
lonuridse, Nycteridae, Rhinolophidae, Hipposideridse, 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 Phyllos- 
tomidae, Desmodontidae, Thyropteridae, Myzopodidae, 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 Molossidae. No distinct third 
phalanx is present in the third, fourth, and fifth fingers of any 
Megachiroptera, or among the Rhinopomidae, Emballonuridae, Noc- 
tilionidae, Nycteridae, Megadermidae, Rhinolophidae, Hipposideridae, 
Natalidae, 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 
