656 KEPTILES — CHELYDRID^. 



somewhat palmate with sharp pointed claws. The color markings being very vanable 

 are of no value as famishing points of distinction. 

 Habitat, Massachusetts, New York, Ohio and Michigan, to Missouri, and South. 



This species is rare, but occurs in eveiy part of the State. Their 

 favorite resorts are dry sandy hills, being rarely found in damp places. 

 They cannot endure rain, but retire to their holes on the approach of a 

 storm. They attain a great age, a specimen mentioned by Allen* must 

 have been at least sixty years old. They probably do not migrate to any 

 great distance from their birth-place, and go into winter quarters by bur- 

 rowing into the ground in September. 



FAMILY CHELYDRID^. SNAPPING TURTLES. 



Head and neck large and powerful ; jaws strong, horny, the apex of upper with a dis- 

 tinct downward curve ; tail long, with a caudal crest of prominent, laterally compressed 

 tubercles ; feet palmate with long claws ; plastron small, cruciform, composed of 

 twelve shields ; aquatic animals of great strength and exceeding ferocity. 



t Head covered with plates ; a row of three scales on each side between the costal and 

 marginal plates ; extralimital t Mackochblts. 



t Head covered with skin Cheltdka. 



Genus CHELYDRA. Schweigger. 



Head large, but smaller than in Macroeliehjs, and covered with soft stin ; upper and 

 hinder part of the orbit projecting beyond the skull; mouth very broad; commissure 

 sinuous; nostiils large; tympanum often concealed; carapax highest medially with 

 ridges on the vertebral and costal plates, which disappear with age ; under side of tail 

 with two rows of large, smooth scales ; no scales between the costal and marginal rows 

 of plates 



Chelydra serpentina Linnffius. 



Snappiug- Turtle. 



lestudo serpentina, LmNiEUS, Daudin, LkConte. 

 Chelonura serpentina, Say, Holbrook, Kirtland, DeKat. 

 Emys serpentina, Gray, Merbem. 

 Emysaurus serpentina, StoRER, Dumeril and Bibron. 

 Chelydra serpentina. Gray, Cope, Allen, Jordon. 



Color olivaceous oi dirty brown above ; plastron, under part of legs, neck, and tail 

 yellow, becoming dull with age; color more or lees disguised by the mud adherent to 

 the animal and carapax ; vertebral shields nearly quadrate, the first with a rounded, 

 sinuous or jagged edge behind; last neural pointed posteriorly; second and third 



♦ Proo. Best. Soc. Nat. Hist. vol. 12, p. 176. 



tOne species, Maerochelys iaceriina {Gyptchelys, Ag.) Eolbrook's N. A. Herp., i, p, 147; 

 Agassiz's Cont., i, p. 414, ranges from Georgia, Alabama, Mississippi, Louisiana, and 

 Texas, north to Illinois and Missouri. 



