CHEIROPTERA. 



597 



and the spinous processes are wanting from 

 the second to the sixth vertebra. The Atlas 

 is large, the dentata small, and its spinous 

 process inconsiderable. The dorsal vertebra 

 are of a very simple construction ; they are 

 almost without spinous processes, which are 

 replaced by a small tubercle : the bodies are, 

 however, much compressed at the sides, so as 

 to form a sort of crest. The vertebral canal 

 is veiy large in this region. These vertebrae 

 are twelve in number in both forms, excepting 

 in some species of the single genus Vespertilio, 

 in which they are only eleven. The lumbar 

 vertebra retain the peculiar characters which 

 have been mentioned as belonging to the 

 dorsal. They are elongated, and still almost 

 devoid of spinous processes ; they are also 

 compressed into a sort of continuous crest. 

 The number of these vertebrae is four in 

 Pteropus, five in Phyllostoma and Vespertilio, 

 six in Rhinolophus, seven in Noctula. 



The sacrum is particularly elongated and 

 narrow, and the spinous processes large. The 

 number of sacral vertebra varies much. In 

 Pteropus (fig. 280) there is but one. In the 

 other genera they are either three or four. In 

 Pteropus the sacrum is united at its extremity 

 to the tuberosities of the ischium. 



The coccygeal vertebra are slender, elon- 

 gated, and nearly cylindrical ; the tail being 

 always included within the flying membrane, 

 the only use of this part is to assist in sup- 

 porting the interfemoral portion of that mem- 

 brane. In most the tail reaches to its margin, 

 in some much beyond, in others only half-way, 

 and in Pteropus (Jig. 280) there is not the least 

 appearance of a tail, there is not even a rudi- 

 ment of acoccygeal bone. The number of these 

 vertebrae is but six in Noctula, twelve in Ves- 

 pertilio and some others. 



The number of vertebrae in the whole co- 

 lumn is said to be less in Pteropus than in any 

 other mammiferous animal, being only twenty- 

 four, namely, 7C+1 2 D+4L-HS=24. 



The ribs are the same in number as the dorsal 

 vertebra. The first rib is very short and 

 remarkably broad, and its cartilage, which is 

 ossified, is still more so. The rest of the ribs 

 follow the usual variations of form. 



The Bats are remarkable for the extraordinary 

 proportional length of their ribs, in which they 

 probably exceed all other Mammifera. 



The sternum is altogether greatly developed 

 in the whole of this order. Its length is con- 

 siderable, and this circumstance,with the length 

 of the ribs, tends to afford a great protection 

 to the thorax in the violent movements re- 

 quired by the act of flight. But the most re- 

 markable peculiarity exhibited in the structure 

 of this part, is the extraordinary lateral deve- 

 lopment of the anterior portion of this bone, 

 termed the manubrium. This expansion is 

 conspicuous in all the Bats, and appears to be 

 intended to afford the strongest possible attach- 

 ment for the clavicles,which are also very much 

 developed. In the genus Rhinolophus (the 

 Horse-shoe Bat), this expansion seems to have 

 reached its maximum of development. Ets 

 breadth is four times as great as its length, and 



yet it is nearly as long as the whole remaining 

 portion of the sternum. The inferior surface 

 of the manubrium is also furnished with a 

 crest, which is continued, though much smal- 

 ler, on the next piece of the sternum ; it varies 

 in size in the different genera. The remaining 

 bones composing the sternum are of nearly equal 

 size. 



The anterior extremity is the part of the 

 skeleton which in the true Cheiroptera offers 

 the most remarkable deviation from the nor- 

 mal form, especially in the metacarpal and pha- 

 langeal bones. 



The clavicle, from the extensive motion of 

 the anterior extremities, requires to be much 

 elongated in these animals ; some of which in 

 fact exhibit proportionally a greater develop- 

 ment of this bone than is to be found in any 

 other order. It is always arched above and 

 intimately articulated both to the scapula and 

 to the sternum, and in some species is half as 

 long as the greatly elongated humerus. As far 

 as I have had an opportunity of observing, 

 the clavicle, as well as the other portions of 

 this extremity, is more developed in the in- 

 sectivorous than in the frugivorous Bats, for the 

 very obvious reason that the former require 

 more extensive powers of flight in the pursuit 

 of their swift and active prey, than the latter 

 in merely flying from place to place, in search 

 of their stationary food. 



The scapula is also developed to the greatest 

 extent, and particularly in the insectivorous 

 Bats. It is greatly elongated towards the base 

 and posterior angle, which in some species 

 reaches nearly to the last rib. The inner 

 surface is very concave, and the fossa above 

 and below the spine are deep, for the attach- 

 ment of the powerful muscles which are in- 

 serted to it. 



The humerus is very long, slender, and cy- 

 lindrical, as may be observed in the skeleton 

 of Pteropus in Jig. 280. The head of the bone 

 is round and large. The whole anterior part 

 of the inferior articulation or elbow-joint cor- 

 responds to the head of the radius. 



The fore-arm consists, as in the other mam- 

 mijera, of the radius and the ulna. The latter 

 bone is, however, in all the Cheiroptera ex- 

 ceedingly small, and in some merely rudimen- 

 tary. In several species of Vespertilio, for 

 instance, it forms nothing more than a flat 

 process, only partially separated from the 

 radius. In the example shewn at fig. 280 

 it is more considerable ; but even here it 

 presents nothing more than a small styliform 

 bone, united to the radius at the head, and 

 diminishing to a thin point, towards the 

 carpal extremity; the olecranon too is wholly 

 wanting. 



The radius, like the other bones of the an- 

 terior extremity, is remarkably elongated, and 

 rather robust. The absence of rotation in the 

 forearm of these animals forms an admirable 

 adaptation to their habits. Not only would 

 the pronation and supination of the hand be 

 wholly useless to them, but at every impulse 

 of their flight such a motion would deprive 

 the whole limb of its resistance to the air, of 



