NORTH AMERICAN BATRACHFA AND REPTILIA. 51 



Family CHELONID^. 



Body liio^hest in front, and widest about the middle; no 

 tooth-like projections on the jaws; carapace heart-shaped. 



A. Costal scales five on each side ; scales around the large 

 median plate on top of head 13 to 20; scales on cheeks 15 to 20; 

 cutting edge of lower jaw not serrated Thalassochelys. 



B. Costal scales four on each side; scales around large 

 median plate on top of head seven. 



a. Scales on cheeks from 7 to 10; cutting edge of lower 

 jaw not serrated Eretmochelys. 



1). Large scales on cheeks 15 to 20; cutting edge of lower 

 jaw deeply serrate Chelonia. 



Genus Thalassochelys, Fitz. 



95. T. caouana^ Linn. Loggerhead Turtle. Head low, 

 broad and fiat; jaw with strong, pointed beaks; shell smooth, 

 subcordiform; vertebral scales 5, costal 10, and marginal 25 to 

 27; scales not imbricate; two nails to each paddle. Entire 

 Atlantic coast. 



Genus Eretmochelts, Fitz. 



96. E. imhricata^ Linn. Tortoise-shell Turtle. Head, low 

 and broad ; anterior part of jaws produced forward into a pro- 

 jecting bill ; scales on shield imbricated, forming thick, hard 

 plates; four pairs of costals; no horny plates on neck; two nails 

 to each paddle. Southern Atlantic coast. 



Genus Chelonia, Brong. 



97. C. mydas^ Schw. Green Turtle. Head high and nar- 

 row; upper jaw slightly notched in front ; lower jaw with a small 

 projection; the sides deeply serrated; l3ody oblong; scales of 

 shield thin, not imbricated; a single nail to each paddle. Atlan- 

 tic coast, south of Long Island. 



Family TPJONYCHID^. 



Head long and narrow; nostrils not subdivided by an inter- 

 nal ridge; edge of upper jaw sharp, and serrated behind. 



Amy da. 

 Head broad ; nostrils subdivided by a ridge which projects 

 from the median wall; edge of upper jaw not serrated. 



Aspidonecte^. 

 1— 



