OP OSSEOUS SYSTEM. 1 1 .'J 



humerus short and widely expanded at both ends, the ole- 

 cranon of great magnitude and extent, the bones of the hand 

 short, fixed, and strong for rapidly excavating the ground, and 

 one of the carpal bones is lengthened and curved forwards 

 to increase the inner surface of this digging instrument. 

 The pelvis and the posterior extremities are very small, the 

 pelvic bones are anchylosed to the sacrum, the pubics are 

 separate in front, and the fibula is reduced to a small process 

 of the tibia as in most other digging and burrowing qua- 

 drupeds. 



The skeletons of the cheiroptera are constructed for flight 

 and present, as in the moles, the anterior portion much more 

 developed than the posterior. The jaws are lengthened for 

 the reception of numerous broad-crowned sharp- tuberculated 

 insectivorous molar teeth. The canine teeth are generally 

 long and pointed, the intermaxillary bones small and imper- 

 fectly ossified, the palatine bones separate, the zygomatic 

 arch is very feeble, and the orbits, for their very small eyes, 

 are continuous with the temporal fossse, as in carnivora. 

 The bones of bats are generally light and compact in their 

 texture and some of their ordinary sutures, as the sagittal, 

 early disappear in the cranium. The orbit is surrounded 

 with a complete osseous margin in the pier opus. In the 

 rhinolophus the intermaxillaries are small, soft, and cartilagi- 

 nous, and contain each but one incisor tooth; and in the 

 nycteris these bones are united by a moveable articulation to 

 the upper jaw-bones, like the moveable upper bill of parrots 

 and cockatoos. The cervical and lumbar regions of the 

 skeleton admit of free motion, and the long iliac bones are 

 often anchylosed to the sacrum as in the feathered tribes. 

 The coccygeal vertebrae are often prolonged to support an in- 

 ter femoral membrane, as in the pteropus and rhinolophus. 

 The long pubic bones scarcely meet at the symphesis, and 

 the cotyloid cavities are directed obliquely backwards which 

 assists in the retroversion of the feet. The scapulae have a 

 broad expanded form, the clavicles are long and strong, the 

 coracoid process is lengthened and curved downwards and 

 inwards, and the fore part of the sternum is often deeply 

 carinated like that of a bird. The long cylindrical humerus 

 is succeeded solely by the radius in the fore-arm, the ulna 

 being reduced to its olecranon, which often forms a separate 



PART I. 1 



