hawkVbill turtle. 8 



formed into tlic most perfect oars, by means of which they 

 are propelled with considerable force and velocity ; " the 

 Green and Hawk-billed in particular," says Audubon, "re- 

 mind you, by their celerity, and the ease of their motions, 

 of the progress of a bird in the air." The head is so placed 

 upon the neck as to allow of the nostrils being readily raised 

 above the surface for the purpose of occasional respiration. 

 The nostrils, also, are furnished with a fleshy valve, which is 

 closed when the animal is submerged, but opens when re- 

 quired for respiration. The food of the Green Turtle con- 

 sists of marine plants, especially the sea wrack, Zostera 

 marina ; and they graze at the bottom of the water, coming 

 at intervals to the surface to breathe. As this mode of 

 taking their food renders them very liable to swallow, with 

 their aliment, a considerable quantity of sea- water, there 

 is a beautiful structure lining the interior of the oesophagus, 

 by which this circumstance is effectually obviated. This 

 consists of a great number of horny pyramidal bodies, with 

 which the w^hole interior of the oesophagus is furnished, 

 all of them directed backwards towards the stomach ; by 

 which means, although the food and the water together can 

 be readily swallowed, yet, when the stomach is contracted for 

 the purpose of regurgitating the water, the food itself is re- 

 tained. " The Hawk-billed species feeds on sea-weeds, crabs, 

 various kinds of shell-fish, and fishes ; the Loggerhead mostly 

 on the fish of conch shells of large size, which they are en- 

 abled, by means of their powerful beak, to crush to pieces 

 with apparently as much ease as a man cracks a walnut. 

 The Trunk Turtle feeds on mollusca, fish, Crustacea, sea- 

 urchins, and various marine plants."* 



Their jaws are strong, and firmly articulated. The horny 

 beak, which so much resembles that of some birds as to 

 have led to the application of the name of HawFs-billed 



* Audub. Amer. Ornith. Biog. II. p. 374. 



B 2 



