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MR. C. TATE REGAN ON THE 
2. ¢NENOCARA GYMNORHYNCHUS. 
? Hypostomus nudiceps Miill, & Trosch. in Schomb. Reis. Brit. Guiana, iii, p. 631 (1848). 
Ancistrus gymnorhynchus Kner, Denkschr. Ak. Wien, vii. 1854, p. 275. 
? Chetostomus nudiceps Giinth. Cat. Fish. y. p. 249 (1864). 
Chelostomus gymnorhynchus Giinth. 1. c.; Liitk. Vid. Medd. 1873, p. 204. 
Closely allied to X. /atifrons. Ilead a little longer than broad, its length 3 times 
in the total length. Diameter of eye 6-7 times in the length of head, 2} times in the 
interorbital width. Snout with a naked margin, without tentacles. 15-14 inter- 
opercular spines. Scutes spinulose, not carinate. D.I7. A.14. A blackish spot 
at the base of the first interradial membrane of the dorsal. 
Venezuela; Guiana. 
5. MENOCARA DOLICHOPTERA. 
Ancistrus dolichopterus Kner, Denkschr. Ak. Wien, vii. 1854, p. 274, pl. iii. fig. 1. 
Chetostomus dolichopterus Giinth. Cat. Fish. v. p. 249 (1864). 
Ancistrus temminkii (non Cuv. & Val.) Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 48; 
Occ. Pap. Cal. Ac. i. 1890, p. 448. 
Depth of body about 42 times in the total length, length of head about 22 times. 
Head 1} times as long as broad and twice as long as deep. Diameter of eye 7 times 
in the length of head, interorbital width 2} times, length of snout 1} times. Length 
of mandibular ramus about 34 times in the interorbital width. Snout with tentacles. 
Interoperculum armed with 8 spines, the longest 7 times in the length of head. 
23-24 scutes in a longitudinal series, 6 between dorsal and adipose fin, 10 between 
anual and caudal. D. I 8-9, the first ray ? the length of head, the last ray, when laid 
back, extending to the spine of the adipose fin ; length of base of dorsal equal to its 
distance from the caudal. A. 14. Pectoral spine extending to anterior 4 of ventral. 
Caudal obliquely truncate, the lowest ray = the length of head. Caudal peduncle 
2! times as long as deep. Brownish, with obscure darker spots or markings; fins 
brownish, with some small dark spots. 
‘Total length 125 mm. 
One specimen: R. Amazon; Guiana, 
4, XENOCARA TEMMINCKII. 
Hypostomus temminckii Cuy. & Val. Hist. Nat. Poiss. xv. p. 514 (1840). 
Ancistrus temminckii Bleek. Nat. Verh. Holl, Maats. xx. 1864, Silures de Suriname, p. 11, pl. i. 
fig. 3, and pl.jii. fig. 2. 
Depth of body 4}-5} times in the total length, length of head 25-24 times. Head 
11-11 times as long as broad and twice as long as deep. Diameter of eye 63-8 times 
in the length of head, interorbital width twice, length of snout 1{-1} times. Length 
of mandibular ramus 53}-4 times in the interorbital width. Snout with tentacles. 
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