CHELONIA. 



riorly. The middle occipital is sub-octagonal, its anterior extremity 

 forming an obtuse concave angle, for the reception of the posterior 

 extremity of the vertex plate ; its lateral angles are contiguous to the 

 parietals and anterior latero-occipitals ; whilst, posteriorly, it comes 

 into contact with the postoccipitals. The latter are somewhat longer 

 than broad, and irregularly angular; a small accessory interoccipital 

 may be seen at the posterior extremity of their commissure. The 

 anterior pair of latero-occipitals is much larger than the posterior 

 pair; both being broader than long. The rim of the orbit is formed 

 superiorly, by the parietal and both pair of frontals, posteriorly by 

 three postorbital plates, and inferiorly by the upper jaw. The middle 

 postorbital is much larger and longer than the two remaining ones ; 

 the uppermost is the smallest ; the lowermost advances nearly as far 

 as the middle of the orbit, There are three temporal shields, irregu- 

 larly angular, subequal with the upper and lower postorbitals, whilst 

 five smaller ones occupy the tympanic region, properly so called. The 

 eyelids are covered with coriaceous plates, the uppermost of which are 

 considerably more developed than the rest. The nostrils, large and 

 subcircular, rest upon a notch at the superior and anterior margin of 

 the upper jaw. An elongated shield may be observed on the side of 

 the lower jaw ; a few small coriaceous plates occupy the space about 

 the angle of the mouth. There are no mental shields ; the skin over 

 the chin and neck is naked, though wrinkled in various ways. The 

 upper surface of the forearm and carpus is protected with polygonal, 

 rather well-developed plates, larger towards their anterior margin than 

 upon their middle ; largest and transversely elongated at their 

 posterior margin. The under surface of the arm is mostly covered 

 with the naked skin, some scattered subelliptical and subcircular 

 plates being observed toward its anterior margin alone. On the palms, 

 the plates are more numerous, quite large, and transversely elongated 

 towards their anterior margin, whilst, posteriorly, the skin is exposed. 

 The digits are all plated ; the two exterior bear a stout claw, and 

 exhibit the largest plates on their surface ; the plates which cover the 

 third and fourth fingers are subquadrangular and well developed, ex- 

 cept the terminal one of each, which is more elongated and irregular 

 in shape. A large subelliptical plate occupies the posterior margin 

 of the flipper at the extremity of the fifth finger. 



The plates which cover the surface of the hind flipper exhibit the 

 same general aspect as those just described. The two exterior toes 



