254 ME. C. TATE KEGAN ON THE 



2. fXENOCAEA GYMNOEHYNCHUS. 



? Hypostomus nudiceps Mull. & Trosch. in Scliorub. Reis. Brit. Guiana, iii. p. 631 (1848). 



Ancistrus gymnorhynchus Kner, Denkschr. Ale. Wien, vii. 1854, p. 275. 



? CluEtostomus nvdiceps Giinth. Cat. Fish. v. p. 249 (1864). 



Chaitostomus gymnorhynchvs Giinth. 1. c. ; Liitk. Vid. Medd. 1873, p. 204. 



Closely allied to X. latifrons. Head 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. 13-14 inter- 

 opercular spines. Scutes spinulose, not carinate. D. 17. A. I 4. A blackish spot 

 at the base of the first interradial membrane of the dorsal. 



Venezuela; Guiana. 



3. Xenocaea dolichopteea. 



Ancistrus dolichopterus Kner, Denkschr. Ak. Wien, vii. 1854, p. 274, pi. iii. fig. 1. 

 Cheetostomus 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 4f times in the total length, length of head about 2f times. 

 Head 14- times as long as broad and twice as long as deep. Diameter of eye 7 times 

 in the length of head, interorbital width 24- times, length of snout If 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, C between dorsal and adipose fit), 10 between 

 anal and caudal. D. I 8-9, the first ray -f 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. I 4. Pectoral spine extending to anterior -g- of ventral. 

 Caudal obliquely truncate, the lowest ray f the length of head. Caudal peduncle 

 24- 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 : B,. Amazon ; Guiana. 



4. XENOCAEA TEMM1XCK1I. 



Hypostomus temminckii Cuv. & Val. Hist. Nat. Poiss. xv. p. 514 (1840). 



Ancistrus temminckii Bleek. Nat. Verli. Holl. Maats. xx. 1864, Silures de Suriname, p. 11, pi. i. 

 fig. 3, and pi. ii. fig. 2. 



Depth of body 4f-5-j times in the total length, length of head 2|— 2-f times. Head 

 l-jj-14^- times as long as broad and twice as long as deep. Diameter of eye Gi-8 times 

 in the length of head, interorbital width twice, length of snout If— If times. Length 

 of mandibular ramus 34—4 times in the interorbital width. Snout with tentacles. 



