FISHES OF THE FAMILY LORICAEIID^E. 241 



29. Ancisteus guentheki, sp. n. (Plate XII. fig. 3.) 

 Plecostomus guttalus (non Cuv. & Val.) Giinth. Cat. Fish. v. p. 237 (1864) . 



Depth of body 6 times in the total length, length of head 3j times. Depth of head 

 twice in its length, diameter of eye 8 times, interorbital width 3^ times, length of 

 snout 1J times. Length of mandibular ramus I-| times in the interorbital width. 

 Head, in other respects, similar to that of A. barbatus, except that the snout has a 

 broad naked area at its tip. Scutes as in A. barbatus. Lower surface of head and 

 abdomen entirely naked. D. I 7, the first ray equal to § the length of head, the last 

 f as long; length of base of dorsal nearly equal to its distance from the adipose fin. 

 A. I 4. Pectoral spine not quite reaching the base of ventral. Caudal obliquely 

 truncate. Caudal peduncle 2j times as long as deep. Colour uniform (in spirit). 



Total length 120 mm. 



One specimen : British Guiana. 



30. f Ancisteus angulicauda. 



Plecostomus angulicauda Steind. Sitzb. Ak. Wien, lxxiv. 1876, p. 672, pi. xii. 



Delturus angulicauda, Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 45, and Occ. Pap. Cal. 

 Ac. i. 1890, p. 437. 



Closely allied to A. barbatus. Length of head about 3^ times in the total length. 

 Head a little broader than long. Diameter of eye about 5J times in the length of 

 head, interorbital width about 3^ times, length of snout If times. Head without 

 keels or ridges. Sides of the head with short bristles in the male, without bristles in 

 the female. Scutes spinulose, not carinate, 24 in a longitudinal series, 7 between 

 dorsal and adipose fin, 10 between anal and caudal. Supraoccipital bordered posteriorly 

 by a pair of scutes. A keel in front of the spine of the adipose fin, formed by 3 or 4 

 scutes. Lower surface of head and abdomen naked. D. I 9, the first ray longer than 

 the head, the last -f as long and connected by a membrane to the two scutes succeeding 

 it. A. I 5. Pectoral spine extending beyond base of ventral. Caudal truncate. 

 Caudal peduncle about 2j times as long as deep. Light brown, without spots. 



Specimens have been recorded up to 270 mm. 



South-eastern Brazil. 



31. f Ancisteus PAEAHYBiE. 



Delturus parahybce Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 45, and Occ. Pap. Cal. Ac. 

 i. 1890, p. 438. 



Differs from the preceding species in having I 10 dorsal rays, 25-27 scutes in a 

 longitudinal series, and all the fins with large round blackish spots. 

 Rio Parahyba. 



2k 2 



