108 FISHES OF WESTERN SOUTH AMERICA 
origin of pectorals; gill membranes free from each other and from the isthmus; 
mouth broad, premaxillary teeth in a rounded band; mandibular band tapered 
backward; teeth of the roof of the mouth in two vomerine patches, two palatine 
patches, and two pterygoid patches; lower jaw much shorter. 
Lateral line with a series of ossicles diminishing toward the end of the dorsal. 
Occipital process extending to the lower plate; fontanel extending to near the 
posterior margin of the eye. 
Dorsal faleate, the spine with feeble hooks behind, slightly roughened in front, 
equal to snout and eye; first ray considerably longer than the spine; adipose dorsal 
3.66 in the length, beginning at the tip of the last dorsal ray; caudal very deeply 
forked, the upper ray prolonged, nearly equal to the combined dorsal and adipose; 
anal truncate; pectoral short and broad, the spine short, heavy, pungent, the outer 
surface rough; the inner surface serrate, the spine about two thirds as long as the 
dorsal spine, the first ray about equal to the length of the dorsal spine. 
Tip of dorsal dark; no distinct markings. 
Genus 18: PSEUDOPLATYSTOMA Bleeker 
Platystoma Agassiz, 1829, Sel. Gen. et Spec. Pisce. Bras., 28, sp. 
Sorubim Spix, 1829, Sel. Gen. et Spec. Pisce. Bras., pls. xii-xv. 
Pseudoplatystoma Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 97; 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sei., I, 207; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 391; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 182. 
Hemiplatystoma Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 97, tagrinwm. 
Type: Silurus fasciatus Linnaeus (part) 
Throughout Amazons, to Surinam 
Head greatly depressed; top of head bony; occipital processes meeting, or 
nearly meeting, dorsal plate; fontanel extending from the middle of the snout to 
behind the eyes and continued as a groove to the occipital; width of mouth about 
equal to the greatest width of the head; upper jaw a little longer than the lower; jaw 
teeth uniform; vomerine teeth constricted in the middle line, and with palatine 
teeth in more or less confluent patches, the two forming a comma-shaped area on 
each side of the palate; gill-rakers short, spinose, not overlapping; caudal deeply 
cleft, the lobes rounded, with the rays much branched; branchiostegals 14-15; 
barbels short. 
51. PSEUDOPLATYSTOMA FASCIATUM (Linnaeus) 
Silurus fasciatus Linnaeus, 1766, Syst. Nat., ed. xii, I, 505; 
Bloch, 1794, Ausl. Fisehe, VIII, 30, pl. 366; 
Bloch and Schneider, 1801, Syst. Ichth., 382. 
Pimelodus fasciatum Lacépéde, 1803, Hist. Nat. Poiss., V, 94, 99, 100. 
Platystoma fasciatum Cuvier and Valenciennes, 1840, Hist. Nat. Poiss., XV, 14; 
Giinther, 1864, Cat. Fish. Brit. Mus., V, 107; 
Cope, 1878, Proc. Amer. Phil. Soc., XVII, 674, Peruvian Amazon; 
