258 TRlONTCniDiE. 



11. Trionyx euphraticus. 



Testudo euphratica, Daml Itcpt. ii. p. 305 (1802). 



rafcht, Olivier, Voy. Emp. Othom. vi. p. 328, pi. xli. (1807). 



Trionyx euphraticus, Geoffr. Ann. Mus. xiv. p. 17 (1809), 

 Gymuopus euphraticus, l)um. ^- Bibr. ii. p. 408 (1835). 

 Tiionvx, sp., Martin, Froc. Zool. Soc. 1840, p. 56. 

 Tyrse'rafoht, Gray, Cat. Tort. p. 49 (1844). _ 

 TriDiiyx rafeht. Gray, Cat. S/i. Mcpt. i. p, 65, pi. xxx. (1855). 

 Eafetus euphraticus, Gray, Proc. Zool. Soc. 1864, p. 81, and Supjil. 

 Cat. Sfi. Rcpt. i. p. 104 (1870), and Proc. Zool. Soc. 1873, p. 05, 

 figs- 

 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 

 vcrmiculate ; a fontanelle persists late in life between the nuchal and 

 the first neural and costal plates. Epiplastra separated from each 

 •other ; entoplastron forming an acute angle ; plastral callosities feebly 

 deyelopcd, 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 ccntim. 

 Tigris and Euphrates. 



a. Ad., stffd., skull separate. Euphrates. W. K. Loftus, Esq. [P.]. 

 h. Ad., stfld. Euphrates. Capt. Chesuey [P.]. 



12. Trionyx emoryi. 



Aspidonectes emoryi, Agassiz, Contr. N, H. U. S. i. p. 407, pi. vi. 



%. 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 bet-^eeu the eyes 

 to the end of the proboscis. 



Length of dorsal disk 30 centim. 



Texas and Rio Grande System. 



a. Hgr., spir., skuU separate. Kio Grande. Smithsonian Instit. 



b-c. Yg., spir. Matamoras, Mexico. Smithsonian Instit. 



