THE TURTLES 



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with claws. They are further characterized by the heart-like form of the carapace, 

 within which the head can be only partially withdrawn; while the plastron is never 

 united by bone to the carapace, and vacuities remain in the latter between the costal 

 and marginal bones either throughout life, or for a very long period. The skull 

 has its temporal fossae completely roofed over by bone, and the vertebrae of the very 

 short tail have the articular cup in front and the ball behind. Entirely marine in 

 their habits, and resorting to the shore only for the purpose of breeding, turtles 

 differ from tortoises and terrapins in that the shells of their eggs are soft. In their 

 entire conformation they are admirably adapted for an aquatic life, the body being 

 depressed to facilitate rapid progress through the water, both the skull and shell 

 being of unusually light and porous structure; the limbs form most perfect paddles, 

 capable of propelling the ani- 

 mals with great speed. The 

 head is placed upon the neck 

 in such a manner as to allow of 

 the nostrils being readily raised 

 above the surface of the water 

 for the purpose of breathing, 

 and the nostrils themselves can 

 be hermetically closed by means 

 of a fleshy valve. The three 

 best-known species of turtles, 

 which are assigned to two gen- 

 era, are inhabitants of all trop- 

 ical and subtropical seas; one 

 species the loggerhead oc- 

 curring in the Mediterranean, 

 and occasionally wandering 

 northward. 



Widely cele- 

 brated as being 

 the source of the far-famed 

 turtle soup of civic banquets, 

 the green turtle (Chelone my- 



das} is one of two species belonging to a genus characterized by the presence of 

 four pairs of costal shields on the carapace, and by the persistence of the vacuities 

 between the costal and marginal bones of the latter throughout life. The plastron 

 is, moreover, distinguished by the presence of an intergular shield between the 

 two gulars; while, as in the second genus, there is a row of inframarginal shields 

 between the marginals and the proper shields of the plastron. The skull is of 

 moderate size in comparison to the shell, with the sockets of the eyes placed 

 nearly vertically, and separated by a broad bar of bone. Such are the characteris- 

 tics common to the two species of the typical genus of the family. The green 

 turtle is specially distinguished by its short beak which is devoid of a hook at 

 the tip, and by the shields of the carapace being in contact by their edges all through 



Green Turtle 



GREEN TURTLE. 



