ANNOTATED LIST OF THE SPECIES 141 
Hypophthalmus perporosus Cope, 1878, Proc. Amer. Phil. Soc., XVII, 673, Nauta; 
Steindachner, 1882, Denksch. KK. Akad. Wiss. Wien, XLVI, 4, Rio Huallaga. 
Hypophthalmus edentulus Castelnau, 1855, Anim. Amér. Sud, Poiss., 47. 
Rio Huallaga and Amazon northward 
15653, 5, 230-3824 mm., Iquitos, Allen, September, 1920. 
15779, 8, 220-302 mm., Iquitos, Allen, September, 1920. 
15780, 2, 248 and 287 mm., Manaos, Brazil, Allen, December, 1920. 
15787, 5, 215-300 mm., Manaos, Brazil, Allen, December, 1920. 
15976, 1, 245 mm., Iquitos, Morris, 1922. 
Known among the inhabitants of Eastern Peru as the maparaté. Conspicuous 
for the extreme width and flatness of the barbels, as well as their jet-black color. 
The barbels may be seen extended forward during locomotion, near the surface 
of the water. Usually found in muddy streams. Steindachner was supplied with 
a Quichua name of mapa-racui. The larger specimens have less black on fins and 
barbels. Those from Brazil have broader, blacker, more taeniiform barbels than 
the Peruvian specimens, especially the mental pair. Our Peruvian specimens, 
15653, have a larger head than the Manaos specimens, being contained more than 
four times in the total length in both cases. 
Our specimens have the dorsal and ventral profiles moderately and uniformly 
convex, except for the elevated dorsal basis and slightly concave head; adipose 
short, elevated, thin; dorsal fin short, its origin well back, in the vertical from the 
tip of the pectoral, its distance from the tip of the snout 1.2 in its distance from the 
base of the middle caudal rays, the dorsal fin elevated, its spine long, smooth, 
slender, D. I, 6; pectoral fins well developed, a half longer than dorsal, with a 
similar spine only three fourths as long as the longest ray; ventral fins very small, 
the longest ray 2.6 in that of the pectoral, origin of fin at middle point of pectoral; 
anal very long, its basis nearly equal to distance of dorsal origin from tip of snout, 
anal rays about 64; caudal deeply forked, its upper lobe the narrower and somewhat 
longer, both lobes, especially the upper, sharply pointed. 
Eye strongly inferior, 9.3 in the head, the interorbital space variable, due to 
the paper-thinness of the skull and elasticity of the opercular region and visceral 
skull; head widest behind posterior nares and behind eyes, narrower midway; snout 
obtusely pointed; jaws equal; gill-membranes cleft to within two eye-lengths of the 
symphysis. The six barbels of moderate length, the longest being the maxillary, 
reaching to near the tip of the pectoral fin. The conspicuous branches of the 
lateral line canal pitted at frequent and irregular intervals; numerous dichotomously 
branching or netted systems of canals on the head. 
Barbels nearly black, all rayed fins tipped in black, extending over distal half 
of anal rays, and on one specimen nearly the entire caudal fin. 
Family VII: Pygidiidae 
Siluroidei trichomycteriformes Bleeker, 1863, Nederl. Tijdsch. Dierk., I, 112. 
Trichomycteridae Gill, 1872, Families Fishes, 19. 
Pygidiidae Eigenmann and Eigenmann, 1888, Amer. Nat., July, 649; 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 316; 
Eigenmann, 1918, Mem. Carnegie Mus., VII, 259-398, pls. xxxvi-lvi, text figs. 1-39. 
