EIGENMANN: the freshwater fishes of BRITISH GUIANA 117 



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

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

 (Roowa). — MtJLLER and Troschel, in Schomburgk, Reisen, III, 1848, 644 

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

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

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

 Potamotrygon hysfrix Eigenmann and Kennedy, Proc. Acad. Nat. Sci. Phila., 



1903, 498 (Asuncion). 

 Toeniura motoro MIjller and Henle, Syst. Beschr. Plagiostomen, 1841, 197 

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

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

 Janeiro). — GtJNTHER, 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). 

 Tceniur a orbignyi Castelnav, Anim. Am. Sud, Poiss., 1855, 102, pi. 49, fig. 1. — 

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

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

 (Ciudad Bolivar) . 

 Trygon millleri 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, HLst. 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 



