Chap. III. GENERA AND SPECIES OF CHELONIOID.^. 381 



and lilunt for some distance in front of the angle. The lower surface of this 

 jaw is turned down, at its iVont end, below its level at the sides. The furrow 

 corresponding to the ridge of the upper jaw is broad at the .symphysis ; it i.s 

 deep below the outer edge, and short, reaching back to where the alveolar edge 

 becomes blunt ; it narrows from the symphysis backward to a point, and at its 

 inner edge rises to a small ridge. The surface within the ridge descends steeply 

 and in one slope to the attachment of the tongue. While the mouth closes, the 

 cutting edges approach each other first at the front and hind ends. The cutting 

 edges are sharp, but not serrated, and there are no teeth or furrows on any 

 part of the horny surface of the mouth. The horny bill is stiff, and projects 

 unusually far beyond the bone of the jaw. 



The arrangement of the scales on the upper surface of the head is very sim- 

 ilar to that of Chelonia, excepting that the row of seven scales, which encircles 

 the large middle scale, is more on the top of the head, and extends less down 

 on its side.s. Two pairs of scales reach from this row forward to the nose. The 

 field of scales on the cheek, like the cheek itself, is small, consisting in number 

 of from seven to ten scales. 



The body is long, narrow, and oval. The marginal rim descends steep and 

 wide over the shoulders, and flares out wide only about the hind end of the 

 body. The scales on the shield are thick and stiif, forming hard plates (the 

 tortoise-shell of commerce) ; they are pointed behind, and imbricated, each one 

 overlapping the one next behind. The large scales on the inner edge of the 

 front limbs are naiTower at their outer than at their inner ends, a character 

 which seems to be connected • with the manner of folding back the limbs. The 

 tortoise-shell is obtained from the species of this genus. 



Modern herpetologists admit, in this genus, only one single species,^ which is 

 believed to be common to the Atlantic and the Pacific Oceans. Having had 

 ample opportunities of comparing specimens from the West Indies with a series 

 of young and adults from the South Seas, preserved in the museum of the 

 Essex Institute in Salem, I have satisfied myself that the shell Turtles of the 

 Pacific Ocean differ specifically from those of the Atlantic. Specimens from the 

 West Indies having first been described under the name of Testudo imbricata, 

 under which both are now confounded, this specific name unquestionably belongs 

 to the Atlantic .species. 



Eretmochelys imbricata, Fitz} This species is common in the West Indies, and 



' Tlmii;rli syiioiiyiiums with the tollnwiiig species, = This species is more ?;eiior!illy liiiown under tlie 



C'iieloiiia rseuihi-Carctlu of Lesson is generally eon- names of Testuilo imliricMta. Chelonia iinlirieala. Ca- 



sidered iis a nominal speeies, whilst Kiihl's Chelonia retta inihrieata. .See, for refereiiees, Dr. Ilolbrook's 



multiscutata is lUKiuestionably a monstrosity. N. Am. llerp., and Diim. and l?ibr. Eri)et. gener. 



