238 Trans. Acad. Sci. of St. Louis. 



of St. Louis, nearly every pond or slough, or slow running 

 creek being inhabited by it. They are seldom found in the 

 Mississippi Eiver, preferring quite muddy water. On a 

 sunny day one may observe small colonies of them lying 

 on partly submerged logs. At the least noise they drop 

 into the water. In February, while the creeks are still 

 covered with ice, they may be seen lying at the bottom. 



92. Chrysemys dorsalis Agassiz. 



Chrysemys picta var. dorsalis. Chrysemys picta part, Clemmys picta 

 var. d. 



Description. — Size and structure of the shell like the preceding, ex- 

 cept that the carapace is more elliptical in outline, and the dorsal 

 scales are proportionally wider. Margin of the costal scales plicated. 

 Sternum uniformly yellow, deep red in spring. The yellow median line 

 along the back is broader than in any other species of Chrysemys. The 

 marginal scales are not so highly ornamented. The head markings as 

 well as those of the feet and tail are similar to the preceding species. 

 The young are nearly circular in outline and the reddish-yellow streak 

 on the back very pronounced. 



Size. — Length of carapace 100 mm.; width 88 mm.; height 33 mm. 

 Length of plastron 87 mm. 



Hahitat. — From the Gulf of Mexico up the Mississippi 

 Eiver to the southeastern part of Missouri. Missouri 

 localities: — Dunklin, Stoddard and Butler Counties. 



Habits. — This is a truly aquatic turtle found in lakes 

 or creeks and common in the extensive overflow of the 

 St. Francis River in the ** Sunken Lands." 



Genus pseudemys. 



Carapace moderately depressed, posterior part of margin slightly ser- 

 rated. Young with a distinct keel. Plastron truncate in front, emargl- 

 nate behind. Wings of pectoral and abdominal plates well developed. 

 Axillary and inguinal plates rather large and about equal in size. 

 Alveolar surface of jaws rather wide, with a median ridge parallel to 

 their margins. Digits 5-4, fully webbed. Fingers with long, slightly 

 curved claws. The clawless fifth toe of the hind foot forms an angular 

 projection on the posterior edge of the foot. Fore legs covered with 

 band-like scales. - '. 



