240 MR. C. TATE REGAN ON THE 
27. ANCISTRUS BARBATUS. 
Hypostomus barbatus Cuv. & Val. Hist. Nat. Poiss. xv. p. 506 (1840); Schomburgk, Fish. 
Guiana, p. 147 (1841) ; Kner, Denksehr. Ak. Wien, vii. 1854, p. 268, pl. ii. fig. 2. 
Hypostomus guttatus Cuv. & Val. t. c. p. 508. 
Plecostomus barbatus Giinth. Cat. Fish. v. p. 237 (1864). 
Pseudancistrus guttatus Bleck. Nat. Verh. Holl. Maats. xx. 1864, Silures de Suriname, p. 10, 
pl. ii. fig. 2, and pl. iii. fig. 3. 
Pseudancistrus barbatus Eigenm. & Eigenm. Proce. Cal. Ac. (2) ii. 1889, p. 45. 
Depth of body 51-53 times in the total length, length of head 3-3} times. Head 
a little longer than broad and twice as long as deep. Diameter of eye 5-7} times in 
the length of head, interorbital width 33-3} times, length of snout 1} times. Length 
of mandibular ramus 14-12 times in the interorbital width. Head without ridges or 
prominences, flat above; snout not naked at tip, rounded, its sides margined with 
bristles, which are short in the female and equal to 2 the length of head in the male ; 
interoperculum moderately movable, armed with similar bristles, which are permanently 
everted, more numerous in the male. Scutes spinulose, not carinate, 24-25 in a 
longitudinal series, 6 between dorsal and adipose fin, 11-12 between anal and caudal. 
Supraoccipital bordered posteriorly by a pair of lateral scutes, and usually to some 
extent by a median scute. Lower surface of head and abdomen naked. D. 1 7, the 
first ray equal to $-4 the length of head, the last $-4 as long; length of base of 
dorsal nearly equal to its distance from the caudal. A. I 4-5. Pectoral spine 
extending a little beyond base of ventral, Caudal slightly and obliquely emarginate 
or truncate. Caudal peduncle about 2} times as long as deep. Brownish, 
with small white spots on the head, and somewhat larger light spots on body 
and fins. 
Total length 260 mm. 
‘Twelve specimens: Guiana. 
28. ANCISTRUS DEPRESSUS. 
Chetostomus depressus Giinth. Proc. Zool. Soc. 1868, p. 232; Steind. Denkschr. Ak. Wien, xliii. 
188], p. 123, pl. v. fig. 1. 
Pseudancistrus depressus Kigenm. & Eigenm. Proc, Cal. Ac. (2) il. 1889, p. 45. 
Depth of body 7 times in the total length, length of head 3 times. Depth of head 
21 times in its length, diameter of eye 5 times, interorbital width 4 times. Length of 
mandibular ramus 1} times in the interorbital width. Caudal peduncle 23 times as 
long as deep. Brownish, with small white spots on head, body, and fin-rays. In all 
other respects similar to the preceding species. 
‘Total length 150 mm, 
One specimen: Surinam. 
