222 Illinois State Lahoratorij of Natural History. 



plates large, triangular. Pectorals and abdominals large, about 

 equal in size, the former not narrowed, quadrangular. A very 

 small axillary. No inguinal. Head of moderate size, convex 

 above, nostrils anterior and near together. Anterior legs with 

 transverse scutes on the anterior surface, digits five. Posterior 

 legs larger than anterior, with small oval scales, digits four, 

 with a large projecting scale in the place of a fifth digit. Claws 

 strong and curved. 



Color above black or brown, with numerous small round 

 or oval spots of yellow. Color beneath brownish yellow, with 

 large black blotches on the outside of the plates. Head black 

 or brown above, with numerous small round yellow spots, be- 

 neath yellow. Legs dark above, pale beneath. Young with a 

 vertebral ridge on the carapace and with a roughened area on 

 the plates surrounded by concentric lines; plates beneath 

 smooth, but with the concentric lines. Spots often obscure. 



Length of carapace, 7; width, 4.75; depth, 2.75. 



Throughout the State, commoner north; formerly abun- 

 dant on the prairies, but rare at present. Normal, Urbana. 



This species is closely related to the box turtle in both 

 structure and habits. It is oftener found in water than the 

 latter, but is essentially a terrestrial species. Its home is on 

 the prairies where it formerly occurred in numbers, but in the 

 better agricultural regions it has been exterminated. 



Ohrysemys, Gray. 

 Gray, Cat. Tortoises, etc., in Coll. Brit. Mus., 1844, p. 27. 



Carapace depressed. Plastron large, truncate before and 

 behind, immovably fixed to the carapace, with no transverse 

 hinge. Wings of pectoral and abdominal plates well devel- 

 oped. Axillary and inguinal plates present and of about equal 

 size. Digits 5-4, several terminal phalanges free, fully webbed, 

 short. Alveolar surfaces of jaws moderately narrow, with a 

 median carina parallel with the margins. 



This genus and Pseudemys are scarcely distinct. The 

 slight differences in the width of the horny covering of the 

 jaws and in the length of tlie digits are not of sufficient im- 

 portance to separate them. To these may be added a differ- 



