1. CHELYDRA.—2. MACROCLEMMYs. 93 
The largest specimen in the Collection measures :—Head and neck 
25 centim., carapace 35, tail 30. 
North America, east of the Rocky Mountains, from Canada to 
Mexico ; Ecuador. 
a. Ad., stftd. 
6, Her., stffd. 
e. Her., spir. 
d, Hgr., spir. 
Lake of Woods. 
Grosse Id., Michigan. 
Grosse Id., Michigan. 
Bloomington, Indiana. 
G. M. Dawson, Esq. 
[C.]. Brit. N. A. 
Boundary Comm. 
Smithsonian Inst. 
Smithsonian Inst. 
C. H. Bollman, Esq. 
eal: 
Meadville, Pennsylvania. Smithsonian Inst. 
Independence, Missouri. Smithsonian Inst. 
TypeeSprings,Tennessee. Smithsonian Inst. 
2 Vie. spin. 
f. Head, spir. 
g. Ye., spi. 
h, t. Her., stffd. Louisiana. 
k. Yg., skel. New Orleans. M. Sallé [C.]. 
G) Nigw, spir: N. America. Lord A. Russell 
(eal 
at , 
m. Her., stffd. N. America. Gen. Hardwicke 
[Pa 
n, 0, p. Ad. & hgyr., stfid. N. America. 
q, r. gr. & yg., spir. N. America. 
s, ¢. Her., skel. N. America. 
wu. Skull. N. America. 
2. Chelydra rossignonii. 
Emysaurus rossignonii, Bocourt, Miss. Se. Mea., Rept. p. 18, pl. v. 
fio. 2 (1870). 
Chelydra rossignonii, Cope, Proce. Ac. Philad. 1872, p. 23; Giinth. 
Biol. C.-Am., Rept. p. 10 (1885). 
This species, which is known only from young specimens, appears 
to be intermediate between C. serpentina and the fossil C. murchi- 
sonit. From the former, it differs in the much broader bridge, 
which measures hardly one seventh of the length of the plastron ; 
abdominal scutes not twice as broad asdeep. Chin with four barbels. 
Mexico; Guatemala. 
2, MACROCLEMMYS. 
Chelonura, part., Holbrook, N. Am. Herp. i. p. 189 (1842). 
Macroclemys, Gray, Cat, Sh. Rept. i. p. 48 (1855). 
Macrochelys, Gray, Proc. Zool. Soc, 1855, p. 200 (1856), and Suppl. 
Cat. Sh. Rept. 1. p. 64 (1870). 
Gypochelys, Agassiz, Contr. N. H, U. S.i. p. 418 (1857). 
Macroclemmys, Strauch, Chelon. Stud. p. 85 (1862). 
Three or four additional or supramarginal shields on each side. 
Orbits lateral. Tail with small scales inferiorly. 
North America. 
