197 
3. On some New Species or FresHwaTER TORTOISES FROM 
Norts America, CEYLON AND AUSTRALIA, IN THE COLLEC- 
TION OF THE British Museum. By Dr. J.E.Gray, F.R.S., 
F.R.G.S. etc. 
Fam. I. Emypip#. 
The freshwater Tortoises which have been referred to the genus 
Emys, as it is at present constituted, may be divided into two very 
distinet genera ; and this is the more advisable as it is extremely 
difficult to distinguish the American species of which it is composed, 
and the separation of any of them by organic characters must facili- 
tate the process. The genera may be thus named and defined :— 
1. Emys. 
The lower jaw rounded beneath, and covered with, the hinder part 
of the horny beak; the toes strong, covered with broad band-like 
scales. 
This genus includes EZ. ornata, FE. scripta, E. Holbrookii, and 
many other species, both Asiatic and American. 
2. PsruDEMYs. 
The lower jaw flattened beneath and covered with a soft skin. The 
toes weak, slender, covered with small scales above, and very broadly 
webbed. 
1. Pseudemys concinna. 
2. P. serrata. 
The genera Batagur and Malaclemys have nearly similar feet, and 
they appear, like Pseudemys, to be the most aquatic animals of the 
family. 
The species which have hitherto been referred to the genus Cisrubo 
differ considerably in their habits, some being nearly terrestrial and 
others almost exclusively aquatic. The examination of the animal 
shows that there are good external characters by which they may be 
divided into natural groups agreeing with their habits and their 
geographic distribution. 
I. The more terrestrial have the front of their legs covered with 
thick, imbricate, triangular scales, the toes only slightly webbed, 
and the sternum broad, hiding the legs when withdrawn, as— 
1. Cistupbo. 
The head rhombic, the forehead flat, and eyes lateral: confined 
to N. America; as 
C. Carolinensis, with four, and C, Mexicana, with only three toes 
on the hind feet. 
2. LuTREeMyYs. 
The head oblong, depressed, with the eyes on the upper part of the 
cheek. Found in Europe, as L. Europea. 
