171 



775. 'Flu- skull of a green Turtle (Ckelone mydtu), in transverse vertical section . 



showing the relative size and shape of the cranial, otocranial, tympanic and 

 temporal cavities, and the osseous roof vaulting over the latter formed by the 

 parietal and squaraosal bones. The columelliform stapes is preserved in situ 

 on the right side. Presented by Prof. Owen, F.R.S. 



776. The right moiety of the cranium of a small Turtle (Ckelone mydat). 



A portion of the transverse parietal plate hat been removed, forming an artificial opening 

 into the temporal fossa, answering to the natural one in the akull of the Crocodile. A por- 

 tion of the aquamoial baa likewise been removed, forming an artificial opening atuwering in 

 the natural one between the Mjuamosal, jugal and postfruutal in the Crocodile. On the inner 

 aide of the cranium the count- of the carotid canal has been exposed between the pterygoid 

 and baxisphenoid. The otocrane, or cavity of the internal ear, is also exposed, thowing the 

 inner surfaces of the exoccipital, paroccipital, superorripital, aluphenoid and tympanic bones, 

 which concur in iu formation. 



Presented by Prof. Owen, F.R.S. 



777. The separated bones of the head of a marine Turtle. They are numbered 



according to the Table of SYNONYMS. Presented by Prof. Owen, F.R.S. 



The following specimens to No. 894 inclusive, of a disarticulated skeleton of the same species of 

 Turtle, prepared from a specimen presented by Mr. Cuff, are designed to facilitate the study of the 

 peculiarities of its singularly modified parts. 



778. The skull of a Turtle (Ckelone mydtu), in horizontal and longitudinal section. 



779. The atlas of the same Ckelone. 



780. The odontoid of the same Ckelone. 



781. The second cervical vertebra of the same Ckelone. 



782. The third cervical vertebra of the same Ckelone. 



783. The fourth cervical vertebra of the same Ckelone. 



784. The fifth cervical vertebra of the same Ckelone. 



785. The sixth cervical vertebra of the same Ckelone 







z2 



