Hurter — Herpetology of Missouri. 235 



Genus chrysemys. 



Alveolar surface of upper jaw rather narrow, widest behind. Median 

 ridge not prominent. Upper jaw with a notch in front, on each side 

 of which there is a small tooth. Shell broad and flattened, no con- 

 centric grooves on shields. Claws long. 



Key^ to the Species op Missouri. 



Carapace smooth and rounded, without a keel and not serrated at 

 the rear margin. 



Bright red markings on upper and lower marginal shields 

 of carapace. Carapace dark olive, the shields with 

 narrow yellowish margins. Plastron blood red in life, 

 with an obsolete oblong dark patch in the middle. 



treleasei. 



Carapace dark olive or brown, the shields with narrow or 

 no yellow margins, but traversed by vein-like yellow 

 lines. Plastron with symmetrical black markings over 

 the larger part. belli. 



Carapace dark olive brown, the shields with narrow yel- 

 lowish margins. The yellow median stripe along the 

 back is broader than in any other species. Plastron 

 plain yellow. dorsalis. 



90. Chrysemys treleasei, n. sp.' Trelease's Turtle. 



Description.- — Carapace depressed, quite smooth on the middle part. 

 No keel in the adult. The young of the first to the third year have a 

 faint keel. Nuchal elongate, nearly rectangular. The second, third and 

 fourth vertebrals are hexagonal, the anterior suture of the second and 

 the posterior one of the fourth concave. The two intermediate sutures 

 are straight or nearly so. The lateral sutures of these't'hree scales have 

 a sinuous projection outward in the middle to connect with the sutures 

 of the costals. Costals plicated longitudinally for nearly one-half from 

 the outer edge. Marginals adjoining the two middle costals alao with 

 one or two longitudinal pliae. Plastron large, as long as the opening of 

 the shell, front and hind edge truncate. The shortest median suture 

 is between the humerals. Inguinal and axillary large, the latter the 

 larger. In old specimens the median and transverse sutures of the 

 plastron are followed by one or two parallel pliae. 



Head moderate, snout short, a little projecting. Upper jaw with a 

 small median notch and a small cusp on each side, the edge not or but 

 slightly serrated. Alveolar surface moderately broad, with a feeble 



* Named in honor of Professor William Trelease, President of the Acad- 

 emy of Science of St. Louis. 



