118 TESTUDINID®. 
Var. mexicana. 
Cistudo (Onychotria) mexicana, Gray, Proc. Zool. Soc, 1849, p. 17, 
IU ats 
kh mexicana, Gray, Cat. Sh. Rept. i. p. 40 (1855), and Suppl. 
p. 19 (1870) ; Bocourt, Miss. Se. Mex., Rept. p.17 (1870); Ginth. - 
Biol. C.-Am., Rept. p. 1 (1885). 
Onychotria mexicana, Duges, La Naturaleza, 1888, p. —. 
Carapace oval, more tectiform; an additional, smaller, vertebral 
shield between the fourth and fifth; second costal shield twice as 
broad as long. Hook of upper jaw notched, bicuspid. No distinct 
web between the digits; only three claws to the hind limb. Cara- 
pace brown with yellow spots or radiating lines; plastron variegated 
brown and yellow. Head uniform yellow above; limbs brown, 
with yellow spots. 
Length of shell 17 centim. 
Mexico. 
a,b. Q, stffd. Mexico. (Types.) 
2. Cistudo ornata. 
Cistudo ornata, Agassiz, Contr. N. H. U.S. i. p. 445, pl. iii. figs, 12 
& 13 (1857). 
Carapace short, rather depressed, the vertebral region flat and 
without any keel or ridge, even in the young; shields as in C. 
carolina. Plastron not closing completely the shell, connected with 
the carapace by a very short but distinct bridge. Hook of upper 
jaw notched. Digits without distinct web. Carapace and plastron 
dark brown or black, elegantly marked with yellow spots and 
radiating lines ; a yellow vertebral line. Head and limbs brownish, 
with yellow spots. 
Length of shell 12 centim. 
Nebraska, Kansas, Lowa, Missouri, [linois. 
a-d. 9 & yg., spir. Southern Bonn, Kansas. Smithsonian Institution. 
e. g, shell. N. America. 
14. NICORIA. 
Chersine, part., Alerrem, Tent. p. 29 (1820). 
Imys, part., Dum. § Brbr. ii. p. 252 (1835) ; Gray, Cat. Tort. p. 14 
(1844), and Cat. Sh. Rept. i. p. 19 (1855); Giiinth. Rept. Brit. 
Ind. p. 21 (1864). 
ey i part., Gray, Proc. Zool. Soc. 1834, p. 100, and Cat. Tort. 
4 
Nice Gray, Cat. Sh. Rept. i. p. 17, and Suppl. p. 26 (1870). 
Clemmys, part., Strauch, Chelon. Stud. p. 28 (1862). 
Rhinoclemmys, Gray, Ann. § Mag. N. H. (3) xii. p. 182 (1863) ; 
and Suppl. Cat. Sh. Rept. i. p. 29. 
Chelopus, part., Cope, Proc. Ac. Philad. 1865, p. 185. 
Melanochelys, Gray, Proc. Zool. Soc. 1869, p. 187, and Suppl. Cat. 
Sh. Rept.i. p. 33. 
Geoclemmys, part., Gray, Suppl. Cat. Sh. Rept. i. p. 26. 
Neural plates mostly hexagonal, short-sided behind, or alternately 
