CHAPTER XIII 
THE ORDER CHIROPTERA 
MAmMALs, having their fore limbs specially modified for flight. 
The forearm consists of a rudimentary ulna, and a long curved 
radius. The carpus has six bones supporting a small pollex and 
four greatly elongated fingers, between which and the sides of 
the body and the hinder extremities a thin expansion of the 
integument (the wing-membrane or patagium) is extended. The 
knee is directed backwards, owing to the rotation of the hind limb 
outwards by the wing-membrane ; a peculiar elongated cartilaginous 
process (the calcar), rarely rudimentary or absent, arising from the 
inner side of the ankle-joint, is directed inwards, and supports part 
of the posterior margin of an accessory membrane of flight, extending 
from the tail or posterior extremity of the body to the hinder limbs 
(the inter-femoral membrane). The penis is pendent; the testes are 
abdominal or inguinal ; the mammary glands thoracic and generally 
postaxillary ; the uterus is simple or with more or less long cornua ; 
the placenta discoidal and deciduate; and the smooth cerebral 
hemispheres do not extend backwards over the cerebellum. The 
dental series includes incisors, canines, premolars, and molars and 
never exceeds 7 2, ¢ 4, p 3, m 4; total 38. 
The animals comprised in this order are at once distinguished 
by the presence of true wings, and this peculiarity is accompanied 
by other modifications of bodily structure having special relation to 
flight. Thus, in contrast to most other mammals, in which the hind 
limbs greatly preponderate in size over the fore, in the present 
order the fore limbs immensely exceed the short and weak hinder 
extremities. The thorax, as giving origin to the great muscles 
which sustain flight, and containing the proportionately large lungs 
and heart, is remarkably capacious, and the ribs are flattened and 
close together; the shoulder-girdle is also greatly developed in 
comparison with the weak pelvic bones. 
Linneus included the Bats among the Primates, mainly on 
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