242 Trans. Acad. Sci. of St. Louis. 



who stated that they were often caught when seining in 

 Spring River, Jasper Co. Spring River flows into the 

 Neosho River, a confluent of the Arkansas. A third speci- 

 men I found dead on the edge of a creek near Paris, 

 Texas. 



Habits. — This terrapin occurs principally in rivers with 

 muddy beds. 



Genus malaclemys. 



Shell depressed with a distinct keel. Bridge wide, with the axillary 

 and inguinal processes well developed, the latter united to the fifth 

 costal plate. Entoplastron lying wholly in front of the suture between 

 the humerals and pectorals. Jaws with the alveolar surface broad to 

 very broad and entirely without a median ridge. Skull without a bony 

 temporal arch. Digits strongly webbed. (Hay.) 



Key to the Species of Missouri. 



Comma-shaped yellow mark behind each eye. Keels of second and 

 third dorsal plate concave before the tubercles. lesueuri. 



Spot behind the eye not comma-shaped. Keels of second and third 

 dorsal plates uniformly convex before the tubercles. 



geograpMca. 



96. Malaclemys lesueuri Gray. Map Turtle. Saw-back 

 Turtle. 



Emys lesueurii, Emys pseudo-geograpMca, Malacoclemmys lesueurii, 

 Malaclemys lesueurii, Malaclemys pseudo-geograpMca, Malaco- 

 clemmys pseudo-geographicus, Clemmys pseudo-geographicn, Orapte- 

 mys lesueurii, Graptemys pseudo-geographica. 



Description. — Shell oval, depressed, rising roof-like to a distinct me- 

 dian keel. Posterior border of some or all of the vertebral scutes with 

 each a prominent tubercle, largest on the second and third vertebrals. 

 Shell strongly serrated behind. Nuchal with a notch in its hinder bor- 

 der. Plastron with its hinder lobe not much over one-half the width 

 of the carapace; a broad shallow notch in its hinder border. Bridge 

 broad and flat, rising little towards the carapace. Head of males 

 small; that of the females rather large. Cutting edge of upper jaw 

 smooth, convex, the jaw not notched in front; the alveolar surface of 

 moderate width, wholly separated in front by soft skin. Lower jaw 

 smooth, concave cutting edges, not hooked at the tip. Limbs well de- 

 veloped; the digits webbed to the bases of the claws. Tail of male, as 

 with most of the turtles, bringing the vent beyond the edge of the car- 

 apace. (Hay.) 



