422 THE PLAGIOSTOIMTA. 



POTAMOTRYGON HYSTRIX. 



Pnstenaqiic dc HumhohU Rottlin, 1829, Ann. sci. nat., 16, p. 104, pi. 3, f. 1-3. 



Trijgon hystrix Muller & Henle, ISil, Plasios., p. 167; Schomdurgk, 1843, Fi.shcs Guiana, p. 180 



pi. 20; d'ORBiGNY, 1847, Voy. Amor. Mer., 5, I'oissons, p. 11, pi. 15; Castelnau, 1855, Anim. 



nouv., Poiss., p. 103; Dumeril, 1865, Elasm., p. 008 (part); GijiiTH., 1870, Cat. fishes Brit, mus., 8, 



p. 482 (part); GoELDi, 1897, Bol. Mus. Para., 2, p. 455. 

 Trygon {Taenura) d'orbignyi Castelnau, 1855, Anim. nouv., Poiss., p. 102, pi. 49, f. 1. 

 Tncnura orbignyi Ditmeril, 1865, Elasm., p. 624; Gijnth., 1870, Cat. fishes Brit, mus., 8, p. 484. 

 Potamotryqon humboldtii Garman, 1877, Proc. Bost. soc. nat. hist., 19, p. 210. 

 Polamotrygon hystnx Eigenmann, 1892, Proc. U. S. nat. mus., 15, p. 25 (name only). 

 Potamotrygon d'orbignyi Eigenmann, 1892, Proc. U. S. nat. mus., 15, p. 25 (name only). 

 Ellipesurus orbignyi Ribeiro, 1907, Arch. Mus. nac, 14, p. 186. 

 Ellipesurus hystrix Ribeiro, 1907, Arch. Mus. nac, 14, p. 185. 



Disk oval, little longer than wide, rounded in front and behind. Mouth 

 moderately undulated, with two papillae at the bottom. Teeth flattened, 

 heart shaped, somewhat sharp in males. Eyelid straight. Upper surfaces 

 rough with small loosely and irregularly distributed stellate-based spines, 

 larger toward the middle and absent from the margins. With age the median 

 spines of the tail and back and those near them become enlarged more numerous . 

 and ridged on the' bases. The tail has a rather closely set row of subcorneal 

 tubercles, from base to spine, and bears a series of smaller ones along each side 

 from base to end. Tail longer than body, rarely entire except on very young, 

 with a serrated spine situated behind the body about two thirds the length of 

 the latter, compressed behind the spine, with cutaneous folds above and below. 

 Similar to P. motoro. 



Back brown with scattered areas of lighter; whitish below, darker toward 

 margins; tail brownish on young, blotched on the sides with darker and lighter, 

 banded behind the spine. 



Muller and Henle gave the localities Surinam, Maracaibo, and Buenos 

 Aires. 



The drawings by Schomburgk and by d'Orbigny agree with the foregoing 

 in shapes and armature but differ somewhat in markings; they appear rusty to 

 greenish brown with numerous small, more or less light-edged, elongate or worm- 

 like spots of darker. The description of P. orbignyi by Castelnau would place 

 it nearer P. motoro; the figure is closer to P. hystrix; it was taken in the Tocan- 

 tins, the locality for P. dumerili, P. miilleri, and P. henlei. A specimen of the 

 Pastenague de Humboldt taken by the Thayer Expedition and sketched with 

 the colors of life has the markings described by Roulin. Apparently it is a 

 young P. hystrix. Roulin did not give a Latin name. 



