OR OSSEOUS SYSTEM. cS 1 



succeed them, and they are firmly lodged in deep alveoli. 

 The vertebrae of the crocodilian animals have for the most 

 part a lengthened narrow body, concave before and convex 

 behind, as in other reptiles. The transverse processes of the 

 cervical vertebrae are very broad and long, and detached like 

 ribs, and impede the lateral movements while they encrease the 

 muscular power of the neck, for carrying off and struggling 

 with their large prey. There are two pairs of false ribs before, 

 and two pairs behind the true ribs. The true ribs have a 

 strong attachment, by fheir lengthened head and prominent 

 tubercle, to the sides of the bodies of the vertebras, and the 

 extremities of their transverse processes. The sternal ribs 

 (Fig. 41. q,) are ossified, and similar ossified ribs are con- 

 tinued along the fore part of the abdomen to the pubis. The 

 scapula and the coracoid bone are separate, more lengthened 

 and narrow than in the lizards, and more thick and solid. 

 The clavicular bone of the lizards is here extended forward 

 below the neck, and the ento- and xiphi-sternal portions 

 are most developed in the sternum. The three pelvic bones 

 are more loose than in other saurians. The short expanded 

 iliac bones (gj) are attached to two broad sacral vertebrae. The 

 ossa ischii (A,) meet in front, and form an expanded symphysis, 

 like most pubic bones ; the pubic bones (i } ) are the most 

 slender, and extend forward from the cotyloid cavity, converg- 

 ing, but without meeting to form a symphysis. The humerus 

 (by) and the femur (#,) are both curved in the direction best 

 calculated to give effect to their movements in the water. 

 The radius (c,) and the ulna (d,) as well as the tibia (/,) 

 and the fibula (m,) are here strong and separate to their 

 extremities, leaving a large interosseous space, and forming 

 a broad and highly moveable articulation at the carpus (e,) 

 and the tarsus (n.) The bones of the meta-carpus, (/,) 

 and meta-tarsus (o,) and the phalanges of the fingers and 

 toes, are long and securely articulated at both ends for their 

 double use in the water and on land. 



The chelonian reptiles differ from the sauria in having the 

 ribs immoveable, and from the serpents in having arms and 

 legs ; but their skeleton retains the ordinary conditions of 

 that of the class in the coarse fibrous texture of the bones, 

 in the want of continuous cavities in the long bones, and 

 in the permanent separation of the cranial and other osseous 



PART I. G 



