eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 227 



Hypostomus squalitus Muller and Troschel, in Schomburgk, Reisen, III, 1848, 



142 (Essequibo; Rio Branco; Takutu). 

 Hypostomus horridus Kner, Denkschr. Akad. Wiss. Wien, VII, 1854, 259. 

 Plecostomus horridus Gunther, Catalogue, V, 1864, 232. — Peters, MB. Akad. 



Wiss. Berlin, 1877, 471 (Calabozo). 

 Plecostomus scopirfarius Cope, Proc. Acad. Nat. Sci. Phila., 1871, 55, 286, pi. 16, 



figs. 1, 2 (Ambyiacu). 

 Plecostomus biseriatus Cope, Proc. Acad. Nat. Sci. Phila., 1871, 285, pi. 16 (Ama- 

 zon). — Eigenmann and Eigenmann, Occasional Papers Cal. Acad. Sci., I, 



1890, 409. 

 ? Plecostomus virescens Cope, Proc. Acad. Nat. Sci. Phila., 1874, 137 (Upper 



Amazon); Proc. Am. Philos. Soc, XVII, 1878, 681 (Peruvian Amazon); 



XXXIII, 1894, 101. — Eigenmann and Eigenmann, Occasional Papers Cal. 



Acad. Sci., I, 1890, 408. 

 Plecostomus villarsi Lutken, Overs. Kgl. Dan. Vidensk.-Selsk. Forh., 1874, 211 



(Caracas). — Steindachner, " Fisch-fauna Magdalenen-Stromes," 1878, 26, 



pi. 7. — Eigenmann and Eigenmann, Occasional Papers Cal. Acad. Sci., I, 



1890, 408. 

 Plecostomus tenuicauda Steindachner, " Fisch-fauna Magdalenen-Stromes," 1878, 



24, pi. 6 (Magdalena); "Fisch-fauna des Cauca," etc., 1880, 11 (Cauca). 

 Plecostomus annce Steindachner, Flussfische Sudamerika's," ii, 1881, 12, pi. 3, 



fig. 2. 



While no specimens were secured, it is not at all improbable that this species 

 will be found in British Guiana. So far it has been recorded only by Schom- 

 burgk, who may have seen the common species of the Essequibo, Plecostomus 

 hemiurus. 



Head 3.33-4; depth 6-7; D. 1,7; A. 1,4. Scutes 28 to 30. Eye 5-11 in the 

 head; interorbital 2.33-2.66; mandibular ramus 3-4 in the interorbital. Width of 

 head 1.13-1.25 in its length, snout 1.75-1.85 times. Eight or nine plates between 

 the dorsals, fourteen to fifteen behind the anal; dorsal spine as long as the head, the 

 last ray half as long. Dark spots on the head, body, and fins, those on the dorsal 

 usually arranged in two series between each pair of rays. 



Pterygoplichthys Gill. 

 Pterygoplichihys Gill, Ann. Lye. Nat. Hist. X. Y., VI, 1858, 408 (duodecimalis) . 

 Liposarcus Gunther, Catalogue, V, 1864, 238 (sp.). 



Type, Hypostomus duodecimalis Cuvier and Valenciennes. 



