eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 221 



front, roughened behind, nearly equal to, or slightly longer than, the pectoral spine. 

 Three or four azygous plates in front of the adipose; caudal forked, the lobes a 

 little longer than the head. 



Color variable; a more or less conspicuous black band across the head at the 

 eyes; dorsal black, or partially or faintly so, the color sometimes continued on the 

 sides, other fins hyaline. Sides profusely spotted, quite plain, or the plates mar- 

 gined with black. 



Family VIII. LORICARIIDCE. 



< Sihiroides Cuvier, Regne Animal, ed. 1, II, 1817, 199. 



= Goniodontes Agassiz, Selecta Gen. et Spec. Pise. Bras., 1829, 1. 

 = Loricata Kner, Denkschr. Akad. Wiss. Wien, VI, 1853, 75. 

 = Loricaroidei Bleeker, Nederl. Tijdschr. Dierk., I, 1863, 77. 



< Hypostomatina Gunther, Catalogue, V, 1864, 11. 



< Loricariidce Gill, Arrangement of the Families of Fishes, 1872, 19. 



= Loricariidce Eigenmann and Eigenmann, Am. Nat., XXII, 1888, 649; Occa- 

 sional Papers Cal. Acad. Sci., I, 1890, 351. 

 > Loricariidce Regan, Trans. Zool. Soc. London, XVII, 1904, 191. 



Sides and back and sometimes the lower surface covered with bony plates, 

 which are sometimes provided with teeth-like spines. Mouth wholly inferior, 

 provided with a broad disk-like lip. Maxillary bones thin, with a terminal barbel, 

 which is partly united with the oval disk; no mental or nasal barbels. Teeth, if 

 present, hooked and usually two-lobed at the tip; the active ones in a single series; 

 premaxillaries separate from each other, box-shaped, and filled with numerous relay 

 teeth; dentaries separate from each other and constructed like the premaxillaries. 

 No teeth on the palate; no frontal or occipital fontanels. Dorsal fin present, 

 situated on the abdominal portion of the vertebral column, and not connected 

 with the occipital by processes. Adipose fin, if present, composed of a spine and a 

 thin membrane. Anal fin short. Gill-membranes joined to the isthmus, the gill- 

 openings restricted to the sides. Intestinal canal elongate, coiled upon itself. 



Key to the Guiana Genera of Loricariidce. 

 a. Tail short; caudal peduncle compressed, cylindrical, or moderately depressed; haemal spines all 

 simple; lower, and fourth upper pharyngeals not toothed; belly naked, or with minute granular 

 plates; intestinal canal very long. (Plecostomince.) 

 b. Premaxillaries and dentaries nearly equal in length. 



c. Opercle and interopercle little and not independently movable; snout granular to its margin. 

 d. Adipose fin present. 



e. Sides and back covered with plates; dorsal with seven rays Plecostomus. 



ee. Sides and back covered with plates; dorsal with thirteen rays Pterygoplichthys. 



