380 



AMERICAN TESTUDINATA. 



Part II. 



II. Eretmochelys, Fitz. 



The genus Eretmochelys was first noticed by Fitzinger^ as distinct from Che- 

 Ionia. The head is low ; its upper surface is broader than in Chelonia, and 

 its descent to the nose less. The mouth is long and narrow. The sides of the 

 upper jaw are compressed, and the front end drawn out forward and downward, 

 so that its lower edge is in advance of the nose, and below the general plane 

 of the edges of the sides. The front end is narrow and blunt, and keeps about 

 the same width from the nose down to the lower edge, Avhich, therefore, is not 

 pointed, but like the curved edge of a chisel. The edges of the sides are nearly 

 straight. The inner vertical surface of this jaw is broad at the hind end, and 

 narro^vs thenceforward for the greater part of its length, but widens for a short 

 distance to the front end. This widening at the front end is not caused by a 

 pit-like depression in the horny roof, but by a gentle rise of the latter at the 

 symphysis. The surface of the horny roof falls from without inward to a ridge, 

 which is divided at the symphysis by a deep transverse depression ; it is most 

 prominent on each side of this depression, and decreases thence backward ; from 

 the front end backward it approaches the outer wall for some distance, and then 

 again recedes from it. The fun-ow between this ridge and the outer wall is 

 widest and deepest at the front end ; it narrows to about midway, and then 

 Avidens again to the hind end ; but this latter widened part is only a slight 

 depression. Within the ridge, the surface rises to its inner edge ; it is as broad 

 at the symphysis as the furrow ; it decreases backward, and vanishes at tlie hind 

 end. The lower jaw is also long and narrow; it is drawn out forward and 

 upward at the front end ; the alveolar edge of this end is not pointed, but 

 curved, and is as high as the angle of the jaw. The alveolar edges at the 

 sides are nearly straight ; they are not sharp for the whole length, but thick 



^ In his Systema Reptilium, published in 1843. 

 In 1844, J. E. Gray, in the Cat. of the Brit. Mus., 

 adopted it, but dianged the name to Caretta. On 

 general grounds of fitness, this name would be accept- 

 able, as it is derived from the vernacular name of the 

 tortoise-shell, the caret of tlie French, and the spe- 

 cies which produces this valuable article is the type of 

 the genus. It might also be said, that, as Merrem ap- 

 plied the name of Caretta to all marine Turtles in the 

 same sense as Brongniart had ap|)lied to them that 

 of Chelonia, when it became necessary, in the pro- 

 gress of science, to subdivide the sea Turtles into sev- 



eral genera, the name of Caretta ought to have been 

 preserved for one of the new genera, as well as that 

 of Chelonia. But, the naturalist who first noticed 

 these generic differences had the unquestional)le right 

 to use his own discretion in adopting any well-framed 

 name he chose for these genera ; and as Fitzinger 

 selected that of Eretmochelys for the Turtle which 

 produces the tortoise-shell, that name must now be 

 retained, and no one has a right to change it here- 

 after. Dumeril and Bibron consider this genus 

 merely as a sub-genus of their Chelonia, which in- 

 cludes all the marine Turtles, except Sphargis. 



