THE TURTLES OF NORTH CAROLINA; WITH A KEY TO THE 

 TURTLES OF THE EASTERN UNITED STATES 



By C. S. Brimley 



The animals known as tortoises, turtles or terrapins, no one of which 

 names by the way has an exact application to any particular group 

 of the order, are distinguished from all other living reptiles by having 

 the body enclosed in a bony shell, leaving only the head, neck and 

 limbs free. This shell consists of two portions, an upper more or less 

 arched portion known as the carapace and a lower, smaller, flattened 

 part known as the plastron. These two are united on each side by 

 a bony bridge or cartilaginous suture. 



The majority of existing turtles have the shell covered with horny 

 plates, which do not agree, either in size, number or position with the 

 bony plates beneath (though on the carapace the general arrangement 

 of both is similar), but in two small groups the shell is covered with 

 a leathery skin instead. 



The classification of turtles seems somewhat unsettled, but we can 

 distinguish without much trouble a few main groups, whatever may 

 be their exact relation to one another. 



1. Athecae. Marine turtles with the shell composed of a mosaic 

 of small hexagonal plates which are free from the ribs and vertebrae, 

 and covered with a leathery black skin, and with seven longitudinal 

 ridges down the back. This group includes only the leatherback 

 turtles, the largest of all existing forms. 



2. Thecaphora. In which the shell is composed of a number of 

 bony plates, agreeing in number with and attached to or composed of 

 the expanded ribs and upper processes of the vertebrae. These are 

 attached to a row of marginal bony plates forming the edge of the 

 shell, and these at the sides to another series of plates forming the 

 plastron. 



The Thecaphora comprise the majority of existing turtles and di- 

 vide into : 



(A) The soft-shelled turtles (Trionj'choidea) in which the shell 

 is flattened, orbicular and imperfectly ossified around the edges, and 

 covered with a leathery skin. The species occur in most parts of the 

 world. 



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