2 CHELONIA. 
course, may be an abnormal condition peculiar to the locality where the specimens were 
obtained, and which unfortunately is not known. They are simply marked “ Mexico.” 
The species seems to penetrate rather far southwards into Mexico, as Bocourt 
mentions it from Tampico and the city of Mexico. 
EMYS. 
Emys, Duméril, Elém. d’ Hist. Nat. 
a. CLEMMYS. 
In Mexico two freshwater Turtles occur (Emys ornata and E. cataspila) in consider- 
able abundance, which are distinguished by a short head, a short and obtuse snout, 
and a more or less depressed shell, which is only slightly and indistinctly rugose, and 
in which the costal scutes are ornamented each by a large ocellated spot more or less 
distinctly surrounded by yellow and darker concentric rings. The sternum is marked 
by symmetrical figures formed by black lines arranged in pairs. These figures never 
form rings on the front part of the sternum, as is the case in an allied species from the 
United States, to which the names of Emys holbrookit and E. elegans have been given. 
On the anal scutes this sternal ornamentation terminates with a more or less straight 
double transverse line. The markings on the sternum are most distinct in the young, 
become pale with age, and may disappear altogether. 
In the adult stage these two Turtles differ merely by the position of the ocellus on 
the two middle costal scutes; if each of the scutes be imagined to be divided into four 
quadrangles, in one species the spot occupies the postero-inferior quadrangle, in the 
other the postero-superior. Gray (Cat. Shield Rept. p. 25) has already noticed this 
distinction ; but unfortunately he referred the young of one of the species to the adult 
of the other, so that his Emys venusta is synonymous with his EZ. ornata. 
Some herpetologists may be inclined to consider both forms as variations; but, until 
the true relations between the two forms are clearly ascertained, it will be better to 
distinguish them by separate names. Most probably Emys ornata will prove to be the 
more southern form. 
1. Emys ornata. (Tab. I.) 
Emys ornata, Gray, Syn. Rept. p. 30 (1831); ? Dum. & Bibr. Erp. Gen. ii. p. 286 (1835) ; Gray, 
Zool. Beech. Voy. p. 93, t. 29. fig. 2 (1839); Dum. & Boc. Miss. Sc. Mex. p. 18, t. 3. 
fig. 1 (1870) ; Sowerby and Lear, Tort. t. 44. 
Emys ornata (part.), Gray, Cat. Tort. B. M. 1844, p. 22; Gray, Cat. Shield Rept. 1855, p. 24 
(not fig.). 
Emys venusta, Gray, Cat. Shield Rept. p. 24, t. 124. 
? Emys valida, Leconte, Proc. Ac. N. Sc. Philad. 1859, p. 7. 
Callichelys ornata (part.), Gray, Ann. & Mag. Nat. Hist. 1863, xii. p.176; Suppl. Cat. Shield Rept. 
1870, p. 48. 
