EIGENMANN: THE FRESHWATER FISHES OF BRITISH GUIANA 117 



enciennes, in d'Orbigny, Voy. Am. Mer., V, ii, 1847, 11, pi. 15 (La Plata 

 to Amazon). — Schomburgk, Fishes Brit. Guiana, II, 1842, 180, pi. 20 

 (Roowa). — Muller and Troschel, in Schomburgk, Rciscn, III, 1848, 644 

 (Rupununi; Takutu; Rcwa). — Castelnau, Anim. Am. Sud, Poiss., 1855, 103 — 

 Dumeril, Hist. Nat. Poiss., I, 1865, 608 (Rio de Janeiro; Lake Maracaibo; 

 Buenos Aires). — Gunther, Catalogue, VIII, 1870, 482 (Santarem; Surinam). 

 Potamotrygon hystrix Eigenmanx and Kennedy, Proc. Acad. Nat. Sci. Phila., 



1903,498 (Asuncion). 

 Tceniura motoro Muller and Henle, Syst. Beschr. Plagiostomen, 1841, 197 

 (Cuyaba). — Muller and Troschel, in Schomburgk, Reisen, III, 1848,642 

 (Mouth of the Zuruma).— Dumeril, Hist. Nat. Poiss., I, 1865, 624 (Rio de 

 Janeiro). — Gunther, Catalogue, VIII, 1870, 484. 

 Trygon garrapa Schomburgk, Fishes Brit, Guiana, II, 1842, 182, pi. 21 (Rio 

 Branco). — Muller and Troschel, in Schomburgk, Reisen, III, 1848, 642 

 (Rupununi; Takutu; Rio Branco). 

 Tceniura orbignyi Castelnau, Anim. Am. Sud, Poiss., 1855, 102, pi. 49, fig. 1 — 

 Dumeril, Hist, Nat. Poiss., I, 1865, 624 (Tocantins). — Gunther, Catalogue, 

 VIII, 1870, 484.— Steindachner, " Flussfische Sudamerika's," i, 1879, 11 

 (Ciudad Bolivar) . 

 Trygon miilleri Castelnau, Anim. Am. Sud, Poiss., 1855, 102, pi. 48, fig. 2.— 



Dumeril, Hist, Nat, Poiss., I, 1865,621 (RioCrixasand Araguay). 

 Trygon henlei Castelnau, Anim. Am. Sud, Poiss., 1855, 102, pi. 48, fig. 3.— 

 Dumeril, Hist. Nat. Poiss., I, 1865, 623 (Tocantins). 

 One specimen, 147 mm. Konawaruk. (C. M. Cat. No. 1737.) 

 Three specimens, 158, 181, and 174 mm. across the disk. Rockstone sand- 

 bank. (C. M. Cat. No. 1738; I. U. Cat. No. 12101.) 



Five papillae behind the teeth of the lower jaw. Oval, disk but little longer 

 than broad, without projecting snout; eye about 2 in the interocular space; 

 interorbital 2 or less in the distance from the tip of the disk to the line between 

 the anterior margins of the eye; middle of back tuberculate, becoming smooth at the 

 margin of the disk; irregularly placed thorns along the middle of the tail in front of 

 the serrated spine, and a lower ventral fold (tails of all the specimens broken a short 

 distance behind the spine). 



Back brown with obscure rounded lighter spots, decreasing in size to fine 

 vermiculations on the fin (garrapa of Schomburgk) ; in the smaller specimens the 

 darker areas about the light spots are intensified into four to seven black spots, 

 two of which are sometimes confluent, forming an hour-glass, or less regular streak 



