258 TRIONYCHID 2. 
11. Trionyx euphraticus. 
Testudo euphratica, Daud. Rept. 1. p. 805 (1802), 
rafcht, Olivier, Voy. Emp. Othom, vi. p. 328, pl. xli. (1807). 
Trionyx euphraticus, Geoffr. Ann. Mus. xiv. p. 17 (1809). 
Gymnopus euphraticus, Dum. § Bibr. ii. p. 498 (1835). 
Trionyx, sp., Martin, Proc. Zool. Soc. 1840, p. 56. 
Tyrse rafeht, Gray, Cat. Tort. p. 49 (1844). 
Trionyx rafeht, Gray, Cat. Sh. Rept.i. p. 65, pl. xxx. (1855). 
Rafetus euphraticus, Gray, Proc. Zool. Soc. 1864, p. 81, and Suppl. 
nee Sh. Rept. i. p. 104 (1870), and Proc, Zool. Soc, 1878, p. 65, 
os. 
Costal plates eight pairs, the last not more than half the size of 
the penultimate, and forming a median suture; a single neural 
between the first pair of costals; plates rather coarsely pitted and 
vermiculate ; a fontanelle persists late in life between the nuchal and 
the first neural and costal plates. Lpiplastra separated from each 
other ; entoplastron forming an acute angle ; plastral callosities feebly 
developed, on the hyo- and hypoplastra. Head moderate, with very 
short proboscis ; snout (on the skull) short, obtuse, about as long as 
the diameter of the orbit, which is double the width of the inter- 
orbital space, and thrice the width of the postorbital arch; mandi- 
bular symphysis narrower than the diameter of the orbit, without 
median ridge. Dark green above, whitish below. 
Length of dorsal disk 37 centim. 
Tigris and Euphrates. 
a. Ad., stffd., skull separate. | Euphrates.~ W. K. Loftus, Esq. [P.]. 
bo, Ad., stffd. Euphrates. Capt. Chesney [P. |. 
12. Trionyx emoryi. 
Aspidonectes emoryi, Agassiz, Contr. N. H. U.S.i. p. 407, pl. vi. 
fig. 4 (1857). 
Closely allied to the two following species, but differing in the 
shorter snout, which hardly equals the diameter of the orbit, the 
shorter proboscis, and the absence of conical tubercles on the an- 
terior border of the dorsal disk. Olive above, young with minute 
black dots and a broad pale margin to the dorsal disk. Head, neck, 
and limbs dotted with black; a light black-edged streak on each 
side of the head, passing through the eye, and uniting with its fellow 
into a large triangular marking, extending from between the eyes 
to the end of the proboscis. 
Length of dorsal disk 30 centim. 
Texas and Rio Grande System. 
a. Her., spir., skull separate. Rio Grande. €mitbsonian Instit. 
b-c. Yg., spir. Matamoras, Mexico. Smithsonian Instit. 
