184 DR. J. E. GRAY ON THE TORTOISES. [ Mar. 11, 
The family Emydide, as now restricted, may be thus divided :— 
Section I. AMpursprociemmys. The alveolar surface of the 
upper and lower jaws linear, narrow, with a sharp outer edge. 
Internal nostrils in front of the palate. Toes short, strong, erect, 
and included in the skin to the claws, or more or less expanded 
and united by a narrow scaly webb to the claws. These spe- 
cies are amphibious, and some of them more or less terrestrial. 
Subsection 1. The temporal muscle only covered with skin, without 
being protected by any band-like zygomatic arch in the skull 
uniting the orbit to the ear-cavity of the temporal bone. Eyes 
lateral. Toes short, strong, conical, free or very slightly 
webbed. Legs covered with short triangular scales. 
Tribe I. GEOEMYDINA. 
1. Geormypa. The alveolar surface of the jaws has not been 
examined. 
2. MELANOCHELYS. 
Subsection 2. The temporal muscle protected on the outer side by 
a distinctly band-like zygomatic arch extending between the 
orbit and the tympanic cavity. 
Tribe Il. GkoctemMMypINA. ‘Toes short, enclosed in the skin to 
the claws. Legs covered with thick, hard, triangular scales. 
Eyes lateral (or subsuperior) ; pupil annular. Jaws with a 
narrow alveolar plate. Internal nostrils in front of the palate. 
* Eyes lateral. 
3. GrocLtemmys, Gray, Cat. Shield Rept. p. 17. 
** Byes subsuperior, on the margin of the crown. 
4. Nicorta, Gray, Cat. Shield Rept. p. 17. 
5. Rurnocitemmys, Fitzinger. 
Tribe III. Emyp1na. Toes strong, short, spreading, covered above 
with bands of transverse shields, united by a narrow web 
to the claws. Jaws with a narrow alveolar surface. Internal 
nostrils in the front of the palate. Head covered with a thin, 
hard skin. Eyes subsuperior, with a dark spot on each side of 
the pupil. 
6. Emys. 
7. CLEMMys. 
8. CurysEmys, Gray, Cat. Shield Rept. p. 32. 
9. Graeremys, Agassiz. Emys §§, Gray, Cat. Shield Rept. 29. 
