157 



aa. Cutting edge of the upper jaw smooth, of the lower ser- 

 rate. Median ridge of the alveohir surface coarsely 

 tuberculated. Shell serrate behind. Head of moderate 

 size. f labyrinthica, p. 158. 



\ concinna, p. 159. 



AA. Alveolar surface of upper jaw of moderate width ; the alveolar 



ridge not tuberculated, at most slightly denticulated. Upper 



jaw with a median notch, but no lateral teeth. (^Trachemys, 



Ag.) 

 a. Head rather small; posterior border of the shell very 

 slightly serrated ; plastron with a shallow notch behind. 

 Plastral scutes each with a central blotch and a dark 

 border. troostii, p. 160. 



aa. Head of moderate size. Shell serrated behind. Plastron 

 with a distinct notch behind. Plastral scutes with a 

 central blotch, their margins not bordered with black. 



elegans, p. 161. 

 AAA. Alveolar surface of the upper jaw rather narrow, widest behind ; 

 the median ridge not prominent. Upper jaw with a notch in 

 front, on each side of which there is a small tooth. 

 {Chrysemys.) 

 a. Costal scutes alternating with the vertebrals, the trans- 

 verse rows not straight, 

 b. Costal scutes without red or yellow bands across them. 



marginata, p. 163. 

 bb. Costal scutes crossed by red or yellow bands. 



bellii. Appendix.. 



aa. Costal scutes placed even with the vertebrals, the rows 



across the carapace being straight. picta. Appendix. 



Chrysemys hieroglyphiea, (Holbrook). 

 Hieroglyphic Terrapin. 



Emys hieroglyphiea, Holbrook, 1842, o^, i, 111, pi. 17; Ptychemys 

 hieroglyphiea, Agassiz, 1857, 4-, !> -434; Chrysemys hieroglyphiea, Boulen- 

 ger, 1889, 84, 76. 



Head unusually small; suont somewhat projecting; upper jaw slightly 

 notched in front; both upper and lower jaws smooth or slightly denticu- 

 lated. Shell greatly depressed, and in large specimens without trace of 

 keel. In specimens five inches long there is a slight keel. Shell some- 

 times smooth, occasionally longitudinally v^'riukled. At its border, 

 especially behind the thighs, the sheli flares outward excessively, in some 

 cases producing an actual concavity in the shell above. Hinder margin. 



