222 MEMOIRS OF THE CARNEGIE MUSEUM 



' eee. Sides and back mostly naked, with a few minute plates near the tail. . .Lithogenes. 

 dd. No adipose fin; a low crest between the dorsal and caudal; margin of snout and head 



granular Corymbophanes. 



cc. Interopercle movable, usually with spines or bristles. 



/. Snout granular to its margin, or with bristles; D. 1,6 or 7. 



g. Sides of the head without bristles Hemiancistrus. 



gg. Sides of the head with bristles, short in the female, much longer in the male. 



Pseudancistrus. 

 //. Snout naked. 



ft. No tentacles Xenocara. 



hit. Snout with tentacles Ancistrus. 



bb. Premaxillaries much shorter than the dentaries and with fewer teeth, not united. Much 



depressed, of small size Lithoxus. 



aa. Tail long, depressed, with a single series of plates on the sides; intestinal canal usually not much 

 longer than the body. .Haemal spines of the vertebrae above the anal bifid; lower and fourth 

 upper pharyngeals toothed. (Loricariinw.) 

 i. Teeth in the jaws in small or moderate number, not setiform; a more or less distinct orbital notch. 

 j. Snout rounded or pointed, not much produced. 



k. Lips with numerous cirri and marginal fringes; no distinct anal plate Loricaria. 



kk. Lips papillose; a distinct anal plate Loricariichthys. 



jj. Snout produced, with a long rostrum. 



/. Snout expanded at the tip, with recurved hooks Hemiodontichthys. 



(II. Snout not expanded Reganella.)* 



ii. Teeth numerous, setiform; orbit circular, without a distinct notch. 

 to. Dorsal opposite the ventrals. 



n. Snout rounded, not produced as a rostrum Harttia. 



(nn. Snout produced into a rostrum. Sides of the head in the male margined with bristles. 



Sturisoma.) 

 toto. Dorsal opposite the anal. Very slender Farlowella. 



Subfamily Plecostomin^e. 



Plecostomus Gronow. 



Plecostomus Gronow, Mus. Ichth., 1, 1754, 24; Zoophyl., 1763, 127 (sp.). — Bleeker, 



Nederl. Tijdschr. Dierk., I, 1863, 77 (brasiliensis) . 

 Hypostomus Lacepede, Hist. Nat. Poiss., V, 1803, 144 (guacari). — Cuvier and 



Valenciennes, Hist. Nat. Poiss., XV, 1840, 489 (plecostomus). 



Type, Plecostomus brasiliensis Bleeker = Plecostomus plecostomus (Linnaeus). 



Snout granular; no spines or bristles about head; an adipose fin; sides and 

 back completely covered with plates. 



A genus of over twenty species, four of which have been recorded from Guiana. 



* Extralimital genera and species, when included in the tables, are in parentheses. 



