ANNOTATED LIST OF THE SPECIES 309 
Subfamily: PROCHILODIN AE 
Genus 170: PROCHILODUS Agassiz 
Prochilodus Agassiz, 1829, Sel. Gen. et Spec. Pisce. Bras., 57; 
EKigenmann and Eigenmann, 1891, Proce. U. S. Nat. Mus., XIV, 48; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 424; 
Eigenmann, 1912, Mem. Carnegie Mus., V, 270. 
Type: Prochilodus argenteus Spix 
Western Ecuador to Rio Magdalena and La Plata 
Both jaws very weak, but with teeth, which are inserted on the lips, movable, 
with a single series on the sides and two in the middle; mouth sucker-like when 
opened, ventral, non-protractile; a procumbent dorsal spine; scales ctenoid, rough. 
427. PROCHILODUS NIGRICANS Agassiz 
Prochilodus nigricans Agassiz, 1829, Sel. Gen. et Spec. Pisce. Bras., 64; 
Giinther, 1866, Ann. Mag. Nat. Hist., (3), XVIII, 30; 
Giinther, 1868, Proc. Zool. Soc. London, 229; 
non Giinther, 1864, Cat. Fish. Brit. Mus., V, 295; 
Steindachner, 1882 (1883), Denksch. KIX. Akad. Wiss. Wien, XLVI, 12, Rio Huallaga, one 
poorly preserved, 245 mm.; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 424; 
Pearson, 1937a, Proc. Cal. Acad. Sci., (4), X XIII, 90, R. Crisnejas. 
Amazon and La Plata valleys 
15664, 5, 153-216 mm., Alto Maranon, Allen, October, 1920. 
15667, 1, 174 mm., Rio Morona, Allen, October, 1920. 
17835, 1, 210 mm., Rio Pachitea, Allen, July, 1920. 
17836, 8, 126-220 mm., Rio Ucayali, Contamana, Allen, August, 1920. 
17837, 2, 215 and 220 mm., Iquitos, Allen, September, 1920. 
17838, 2, 142 and 149 mm., Pto. Melendez, Alto Maranon, Allen, October, 1920. 
17839, 1, 228 mm., Rio Pichis, Pto. Bermudez, Allen, July, 1920. 
17840, 6, 142-180 mm., mouth Rio Pacaya, Allen, August, 1920. 
17841, 8, 110-192 mm., Lago Cashiboya, Allen, August, 1920. 
17842, 1, 315 mm., Lago Sanango, Yurimaguas, Allen, November, 1920. 
Ginther, in comparing Bartlett’s material from the Peruvian Amazon with 
that which he had catalogued as P. nigricans from the Essequibo, identified the 
former as nigricans and the Guiana material as rubrotaeniatus of Schomburgk. The 
Amazon form has somewhat smaller scales, 10—48—9; depth 3 in standard length. 
In our collections the following notes are applicable: 
Margins of scales form a series of longitudinal, dark, wavy lines; general 
color dark blue to blue-black; patch of blue-black on the operculum; about 11 faint 
vertical blue bands in the younger; iris yellow; dorsal and caudal fins with narrow, 
irregular, blue-black bands; rhombic scale-pattern above the lateral line. 
The flesh of this species softens in preservative, regardless of care, and assumes 
a bad odor, with a shriveling of the entire specimen. It is one of the three types 
of fishes found in greatest numbers running upstream during the creciente, or flood- 
stages of the rivers (the other two being various Mylinae and Leporinus). These 
