118 FISHES OF WESTERN SOUTH AMERICA 
63. CENTROMOCHLUS STEINDACHNERI Gill 
Centromochlus steindachneri Gill, 1870, Proce. Acad. Nat. Sei. Phila., XXII, 95, Napo or Maranon; 
Eigenmann and Higenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 268; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 395. 
Reported only from the Maranon or its tributaries. 
15903, 2, 74 and 77 mm., Pebas, University of Michigan Museum. 
64. CENTROMOCHLUS PERUGIAE Steindachner 
Centromochlus perugiae Steindachner, 1882 (1883), Denksch. KIx. Akad. Wiss. Wien, XLVI, 29, 
pl. vu, figs. 2-2a, Canelos; 
Higenmann and EKigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 270; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 395. 
Known only from the Canelos specimens. 
65. CENTROMOCHLUS GYRINUS Eigenmann and Allen, sp. nov. 
Plate V, fig. 4 
15795, 1, 55 mm., type, brook near Rio Itaya, Iquitos, Allen, September, 1920. 
Head 4.3; depth 3.5; D. I, 6; A. 12; P. I, 4; caudal forked, with numerous 
fulera forward to adipose and anal fins; adipose well marked, merging forward into 
the back; dorsal short, the spine heavy, sharply striate on the sides; spine broad 
in front with graduated serrae, smooth behind, shorter than head; pectoral spine 
heavy, longer than head, with antrorse to straight hooks in front, and retrorse hooks 
behind; ventral with six rays reaching beyond the anus, not quite to the anal papilla; 
anal papilla fitting into the notch of the anal; anal base contracted. 
Lower jaw projecting; Jaws with narrow bands of firm teeth; maxillary barbel 
to tip of humeral process; mental barbels reaching beyond base of postmental, the 
latter not to base of pectoral; humeral process striate and a series of tubercles; 
frontal ovate, not open in front, about equal to the eye; eye about 3.3 in the head, 
2.5 in the interorbital, 5 in snout; width of head slightly less than its length; spotted 
and streaked. 
Near to C. intermedius, and differing in the greater depth, somewhat longer 
head, and larger eye; anal longer. 
Genus 28: TRACHYCORYSTES Bleeker 
Trachycorystes Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 88; 
Kigenmann and Kigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 272; 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 395. 
Type: Trachycorystes typus Bleeker 
Rio Magdalena and Peru to Rio de Janeiro 
Separable from the preceding by the much longer anal, 19-41; caudal truncate 
or emarginate; mental barbels paired off; lower jaw slightly prolonged; teeth villi- 
