76 TESTUDINID&®. 
4. Chrysemys troostii. 
Emys troostii, Holbr. N. Am. Herp. i. p. 128, pl. xx. (1842); Gray, 
Cat. Tort. p. 42 (1844) ; A. Dum. Cat. Meth. Rept. p. 10 (1851) ; 
Gray, Cat. Sh. Rept. i. p. 28 (1855). 
Trachemys troostii, Agass. Contr. N. H. U. 8S. i. p. 435 (1857) ; 
Gray, Suppl. Cat. Sh. Rept. i. p. 48 (1870). 
Pseudemys troostii, Cope, Check-List N. Am. Rept. p. 53 (1875). 
Shell subround, much depressed, ecarinate and smooth in the 
adult, very slightly serrated behind; nuchalalmost linear. Plastron 
slightly emarginate behind; the longest median suture is that 
between the abdominals, next comes that between the anals, shortest 
of all that between the humerals; axillary and inguinal shields 
present. Head small, oval, and pointed; jaws as in C. scripta. 
Digits broadly webbed, claws very long in the male, Tail nearly 
one third the length of the shell in the male. Carapace dusky, 
tinged with green; plastron brownish yellow, with a large, black 
blotch on each shield ; these spots are liable to become blended or 
altogether obsolete. Head dusky, with very obscure rays of 
brownish yellow ; no bands on the upper surface of the neck. 
Length of shell 20 centim. 
Missouri, Illinois, Tennessee, Mississippi. 
I should have regarded the single specimen, type of Gray’s FE. 
olivacea, as belonging to this species, were it not that the plastron is 
ornamented all over with undulated dark bands somewhat as in C. . 
oregonensis. It may perhaps be considered a variety of C. troostw. 
? Chrysemys olivacea. 
Emys olivacea, Gray, Cat. Sh. Rept. i. p. 80, pl. xii. c (1855). 
Clemmys olivacea, Strauch, Chelon. Stud. p. 82 (1862). 
Redamia olivacea, Gray, Suppl. Cat. Sh. Rept. 1. p. 86 (1870), and 
Ann. & Mag. N. H. (4) x. p. 54 (1872). 
a. Her. 6, stffd. a) Dr. J. E. Gray [P.]. (Type.) 
5. Chrysemys hieroglyphica. 
Emys hieroglyphica, Holbr. N. Am. Herp. i. p. 111, pl. xvii. (1842) ; 
Gray, Cat. Tort. p. 26 (1844) (not specimen); Ad. Dum. Cat. 
Méth. Rept. p. 12 (1851). 
Pseudemys ? hieroglyphica, Gray, Cat. Sh. Rept. i. p. 84 (1855), and 
Suppl. p. 47 (1870). 
Ptychemys hieroglyphica, Agass. Contr. N. H. U. S. i. p. 484 
(1857). 
Clemmys hieroglyphica, Strauch, Chelon. Stud. p. 33 (1862), and 
Verth. Schildkr. p. 86 (1865). 
Shell oval, much depressed, ecarinate and smooth in the adult, 
posterior border serrated; nuchal small, narrow; first vertebral 
shield urceolate. Plastron emarginate behind, the longest median 
