roA'To/sss .-i.vri tcj^ties. 



s6s 



teinlint; into the tissue between neighliouriiii; spinous processes, and 

 supertieially up to the tissue whieh has ditTerenti;Ued into the thin 

 layer ofeonneeiive tissue below the scales. 



The ventral shield or plastron consists of dernial bones ; according 

 to some, three anterior pieces represent clavicles and ictercla\ icle. 



The cervical vertebr.x? have at most little rudiments of ribs, are 

 remarkably varied as regards their articular faces, and give the neck 

 many possibilities of motion. There are no lumbar vertebra-. 



The bones ot the skull are inimovabh' united : there are no ossified 

 alisphenoids, but downward prolongations o( the large jwrietals take 

 their place : neither presphenoid nor orbitosphenoids are ossilied ; there 

 are no distinct nas,il bones in modern Chelonians ; the premaNillv are 

 very small ; there are no teeth : there is a eonipletc bony palate formed 



FlO. loj. — Internal view of skeleton of Turtle. (From 

 Edinburgh Musemii of Science and .\rt.^ 



.V. humerus ; .s",". sc.\pul.i. running dors.iUy ; .\ cor.icoid ; (■..-, 

 epitx^ri\coiiI ; /..". pre-oor.\coid : .'', pul-es ; :'.'. ilium, running 

 vionvxliy ; /s. ischium ; .-'. femur. 



in great pojl from the iimction of the pter\ golds with the basisphenoid 

 and with one another. 



There is Jto sternunt. 



The pectoral girdle on each side consists of a dorsal scapula attached 

 to the c-araivrce, a ventral coracoid bearing terminally a small epicora- 

 coid, and anterior to the coi-acoid a '" precoracoid." 



The pelvic girdle consists of t.lors.tl ilia aitachet.1 to the c.uapace. aiv 

 terior pubes t\iscd in a s\inph\'sis, and posterior ischia siittilarly fused. 



The girdles originally lie in t'ront of. or behind the ribs, but .vre over- 

 arched bv the caiapace in [lie course of its development. 



