656 REPTILES—-CHELYDRIDA. 
somewhat palmate with sharp pointed claws. The color markings being very variable 
are of no value as furnishing points of distinction. 
Habitat, Massachusetts, New York, Ohio and Michigan, to Missouri, and South. 
This species is rare, but occurs in every part of the State. Their 
favorite resorts are dry sandy hiils, 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 CHL Y DRIED Al SNA PPUN Ge ES. 
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 
tabercies; feet palmate with long claws; plastron small, cruciform, composed of 
‘twelve shields; aquatic animals of great strength and exceeding ferocity. 
+ Head covered with plates; a row of three scales on each side between the costal and 
marginal plates; extralimital. : : : ° : : . +t MACROCHELYS. 
t Head covered with skin. . ; ‘ : A : i ‘ ; CHELYDRA. 
GENUS CHELYDRA. Schweigger. 
Head large, but smaller than in Macrochelys, and covered with soft skin; upper and 
hinder part of the orbit projecting beyond the skull; mouth very broad; commissure 
sinuous; nostrils 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 Linneeus. 
Snapping Turtle. 
Testudo serpentina, LENNZUS, DAUDIN, LECONTE. 
Chelonura serpentina, SAY, HOLBROOK, KIRTLAND, DEKAY. 
Emys serpentina, GRAY, MERREM. 
Emysaurus serpentina, STORER, DUMERIL and BIBRON. 
Chelydra serpentina, GRAY, COPE, ALLEN, JORDON. 
Color olivacecus o1 dirty brown above; plastron, under part of legs, neck, and tail 
yellow, becoming dull with age; color more or less 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 
* Proc. Bost. Soc. Nat. Hist. vol. 12, p. 176. 
+One species, Macrochelys lacertina (Gypochelys, Ag.) Holbrook’s N. A. Herp., i, p. 147; 
Agassiz’s Cont., i, p. 414, ranges from Georgia, Alabama, Mississippi, Louisiana, and 
YVexas, north to Illinois and Missouri. 
