Reptiles and Amphibians of Illinois. 243 



Macroclemys lacertina, Schw. Alligator Snapper. 



Chelydra lacertina, Schweigger, Prod. Mon. Chel., 1814, p. 23. 

 Chelonura temminckii, Holbr., N. A. Herp., 1842, 1., p. 147, pi. 



24.— De Kay, Nat. Hist. N. Y., I., Zool. III., Kept, and 



Amph., 1842, p. 9. 

 QypochehjH lacertina, Agassiz, L., Contr. Nat. Hist. U. S., 1857, 



I., p. 414; II., pi. 5, lig. 23-27. 

 Macrochelys lacertina, Davis and Rice, Bull. 111. State Lab. Nat. 



Hist.. I., No. 5, 1883, p. 53; Bull. Chicago Acad. Sci., 1883. 



Length of adults two feet or more. Head very large, with 

 small imbedded plates above; jaws strong, the upper hooked. 

 Shell with a deep channel ou each side of the middle line, 

 leaving three longitudinal convex ridges; emarginate and 

 toothed behind. Tail long, without the elevated dorsal plates 

 of Chelydra serpentina. Skin with numerous short tentacles. 



Quiney, Cairo, Grayville (Ridgway), Union county (C. W. 

 Butler). 



This large species is similar to the common snapping tur- 

 tle. It inhabits the larger streams of the south part of the 

 State, though as Dr. Hoy has observed it in Wisconsin, it 

 probably occurs occasionally in northern Illinois. It attains 

 an unusual size, even exceeding in this respect the commoner 

 species. Mr. R. Ridgway saw a specimen at Grayville, 111., 

 which was "large enough to walk with a man standing on his 

 back." A large example in the Illinois State Laboratory col- 

 lection weighed when alive over eighty pounds. The width of 

 the shell at the bridge of the plastron was 17.50 inches; the 

 length of carapace 22.50 inches; and its depth 7.50 inches. 

 The head measured 6.50 inches in width. Orbit one inch in 

 diameter; eye small; iris black, with brown bars radiating 

 from the pupil. 



Chelydra, Schweigger. 



Schweigger, Prod. Mon. Chel., 1814, p. 23, 

 Cope, Proc. Acad. Nat. Sci., Phila., 1872, p. 23. 



Carapace uniformly convex in adults, obscurely channeled 

 on each side of the middle line in young, with a single row of 

 marginal plates. Plastron small, with nine or ten plates; 

 bridges narrow, each covered by an elongate plate ( not repre- 



