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THE ANATOMY OF ■VERTEBRATED ANIMALS. 



The anterior caudal vertebrse have no transverse processes, 

 but possess ribs which may not become anchylosed with the 

 centra. Thus the tail and the neck are the only regions of 

 the spinal column of a Chelonian which are flexible. 



In the skulls of the Ghelonia all the bones, except the 

 mandible and the hyoidean arch, are immovably united to- 

 gether. 



In the occipital segment of the adult, the supra-occipital 

 is united with the epiotic, but the ex-occipital usually remains 

 perfectly distinct from the opisthotic. The basisphenoid is 

 large and distinct. The alisphenoidal region remains unossi- 

 fied ; but the large parietals send down a prolongation on 

 each side, which plays the part of an alisphenoid. Neither 

 the presphenoid nor the orbitosphenoids are represented by 



Tia. 66. — Lonffitudinal sections of the skull of the Turtle. The upper fig:ure represents the 

 entire skull witli the outline of tlie brain in ftiiit ; the lower gives a tarffer view of the 

 iimer face of the bones of the p-^torior moiety of the skull. 



