ORGANS OF SUPPORT, 



elements. The cervical and the coccygeal vertebrae are those 

 which alone are moveable, and nearly throughout the 

 whole column their bodies present the usual concavity at 

 their anterior end, and convex termination behind. The 

 vertebrae of the trunk have a lengthened form, as seen in 

 the caretta caouana (Fig. 42,) and their bodies, their laminae, 

 and their spinous processes are connected only by sutures. 

 There are eight pairs of ribs united to each other by sutures, 

 and attached between the bodies of the vertebrae. By their 

 union with each other, and with the expanded spinous pro- 

 cesses of the dorsal vertebrae, they form the upper shield 

 or carapace. The lower shield, or plastron, is formed by 

 the nine elements of the sternum, and these two parts are 

 attached to each other, by the sternal appendices (&,) which 

 admit of motion in the 

 turtles. The scapulae 

 (a,) are generally cylin- 

 drical bones more or less 

 lengthened, extending 

 from the sides of the 

 first pair of dorsal ver- 

 tebrae to the glenoid ca- 

 vity for the head of the 

 humerus, and they are 

 anchylosed to the cora- 

 coid bones (,) which 

 converge and have their 



free ends attached to the interior of the ento-sternal bone. 

 The two clavicles (c,) are separated by suture from the 

 scapulae, and are generally flat and expanded at their free 

 extremities, which extend backward and inwards. The ver- 

 tebrae composing the sacrum are anchylosed to each other, 

 and from their sides extend downwards and outwards two 

 short, cylindrical, iliac bones (/,) which enter into the forma- 

 tion of the cotyloid cavity, like the two other pelvic bones, 

 the ossa ischii, which meet in front, as in other reptiles, and 

 the two broad expanded pubic bones (i,) which generally 

 send upwards obliquely a large process like the marsupial 

 bones of mammalia. In the sternum of the land tortoise 

 (Fig. 43. 1.) the nine elements are firmly united to each 

 other by sutures, and also in the same manner to the sternal 



