228 MEMOIRS OF THE CARNEGIE MUSEUM 



94. Pterygoplichthys multiradiatus (Hancock) . 

 Hypostomus multirndiatm Hancock, Zool. Journ., IV, 1828, 226 (Demerara). 

 Liposurcns multiradiatus Gunther, Catalogue, V, 1864, 238 (Demerara). 

 Pterygoplichthys multiradiatus Eigenmann and Eigenmann, Occasional Papers Cal. 



Acad. Sci., I, 1890, 433; Proc. U. S. Nat. IVIus., XIV, 1891, 42.— Eigenmann, 



Repts. Princeton Univ. Exp. Patagonia, III, 1910, 408. 



The following description is by Gunther and is based on the type in the 

 British Museum: 



"D. 1/13. A. 5. P. 1/6. V. 1/5. L. lat. 29. 



" Head not depressed, its length being two-sevenths of the total (without 

 caudal); a rather prominent ridge runs from the eye to below the nostril; occiput 

 with a rather elevated ridge, scutes of the nape bicarinate. Barbel longer than the 

 eye, which is rather small, its diameter being nearly one-fourth of the width of the 

 interorbital space. Interoperculum without any spines. Thorax and belly entirely 

 granulated. Dorsal fin much longer than high, the length of its base being equal 

 to its distance from the extremity of the snout; the length of its anterior rays 

 equals that of the head; there are six scutes between the two dorsal fins. (Caudal 

 fin injured.) Eleven scutes between anal and caudal. The pectoral spine does 

 not extend on to the middle of the ventral. Scutes of the body with a serrated 

 keel. Ferruginous grey." 



Lithogenes Eigenmann. 

 Lithogenes Eigenmann, Ann. Carnegie Mus., VI, 1909, 6. 



With the characters of Plecostomus, but the dermal armature reduced to a 

 few ossicles on the back behind the adipose and along a median line from above the 

 origin of the anal to the caudal. 



95. Lithogenes villosus Eigenmann. (Plate XXVI, figs. 2-4.) 

 Lithogenes villosus Eigenmann, Ann. Carnegie Mus., VI, 1909, 6. 



Type unique, 44 mm. Aruataima Falls, Upper Potaro. (Carnegie Museum 

 Catalog of Fishes No. 1002.) 



Head 3.5; depth 7; D. 8; V. 1,4; P. 1,8; eye 6 in snout, 8 in head, 2.75 in 

 interorbital; width of head equaling snout and orbit; width behind the pectorals 

 about one-fifth greater than the height. 



Oral disk large, margined by a series of incisions; lips smooth, with the faintest 

 rugosities; a bunch of about twenty-five blunt villi in immediate association with 

 the dentary; barbel equal to prenasal part of the snout, measuring from the base 



