Cheiroptera. ^MAMAIALIA. Cheiroptera. 
discover an increase of development of the other bones 
which enter into the constitution of the shoulder. The 
clavicles are elongated and much arched superiorly, the 
bladebone or scapula being likewise very surprisingly 
developed, more especially in the insect-devouring 
species. All these arrangements beautifully illustrate 
the adaptability of this mechanism to the peculiar habits 
of the Cheiroptera, while they at the same time afford 
to the unprejudiced truth-seeker the most satisfactory 
evidences of creative design. The teleological argu- 
ment, indeed, may be still more vigorously enforced by 
a consideration of the osseous elements which enter 
into the formation of the arm, forearm, and hand. To 
a certain extent we have already touched upon this 
mechanism, when speaking of the characteristic function 
of flight. It is here, therefore, only necessary further 
to observe, that the upper extremity of the humerus or 
first bone of the arm is large and rounded, while the 
remainder is cylindrical and slender throughout. The 
two bones of the forearm, namely the radius and ulna, 
are curiously modified ; the former being extremely 
long, and the latter only faintly represented by a 
slender styliform process, or in some cases by a mere 
rudimentary flat bony nodule. By this significant 
disposition of parts all rotatory motion is effectually 
prevented, and those movements of pronation and 
supination, so essential to the welfare of the human 
and quadrumanous species, are entirely dispensed 
with. Had not these changes of structure been intro- 
duced, the comfort, nay the very existence of these 
creatures, would have been jeopardized. Such is the 
foresight of the Divine Architect! And before con- 
cluding this part of the subject, we have further to 
observe that six small bones enter into the framework 
of the wrist, two behind, and four in front ; one of the 
former row being singularly bulky, probably because 
tw'o other carpal bones, usually assumed to be absent, 
do in reality enter into its constitution. Succeeding 
these are the immensely elongated metacarpals and 
wire-like fingers, the phalanges of which diverge from 
one another in the expanded condition of the wing, and 
spread out to reach the lower margin of the elastic skin 
membrane formerly described. The second digit is 
the shortest, and the third the longest, while the thumb 
is comparatively insignificant, and terminated by a 
hooked phalanx. Finally, the bones of the pelvis, and 
those of the lower limb, although they share in the 
general diminution of the osseous fabric quantitively, 
do not in other respects relatively exhibit those devia- 
tions from the normal type of skeletal structure which 
obtain in the shoulder and superior extremities. 
Before proceeding to consider’ the habits of Cheir- 
optera, there are several other interesting peculiarities 
of organization which cannot pass unnoticed. One of 
the most important of these is the great development 
of the ears among those bats living upon insects. In 
some species the external auricles attain a prodigious 
size (fig. 10), being frequently as large as the head, and 
occasionally nearly as long as the entire body ; and 
this curious feature is, moreover, combined with an 
increased development of the internal acoustic appar- 
atus, and a special enlargement of that part of the 
auditory organ termed the cochlea. The eyes of bats are 
VoT,. T. 7 
49 
small, and in those kinds which have large ears they 
are almost concealed from view. The skin, generally, is 
Fig. 10. 
Head of the I.ong-eared Bat (Plecotus auritus). 
clothed with a soft downy hair, except on the winged 
and interfemoral expansions. The sense of smell is 
remarkably acute, more particularl}^ in the insect- 
hunting group. Here again we find an increased 
development of the external organ, precisely analogous 
to the external ear. Certain individuals are provided 
with leaf-like appendages attached to the nostrils, and 
consequently we are fairly entitled to presume that, 
as in the case of hearing, the auricles are created with 
the obvious intention of catching sonorous vibrations, 
so also are the nasal leaflets designed to collect the 
odorous particles emitted from the bodies of the insects 
on which these animals prey (fig. 11). The sense of 
touch is likewise exceedingly sharp. F or a long time 
Fig. 11 
Head of the Greater Horse-shoe Bat (Rhinolophus ferrum-equinuiu). 
it was a question with naturalists how the Cheiroptera 
regulated their flight in caves and recesses of almost 
absolute darkness, there being no doubt as to the well 
ascertained fact that their movements, under these 
circumstances, were conducted with the same skill, 
ease, and rapidity as in twilight. To solve this problem 
the eminent physiologist, Spallanzani, instituted a series 
of cruel experiments. He actually deprived a number 
of bats of their sight by extracting the eyes, and filling 
the sockets with pieces of leather. They were then 
