250 MR. C. TATE REGAN ON THE 
11. {Cu xTOSTOMUS BRANICKI. 
Chatostomus branickii Steind. Denkschr. Ak. Wien, xliii. 1881, p. 118, pl. vi. fig. 1. 
Length of head 5 times in the total length. Head as broad as long and about 
13 times as long as deep. Diameter of eye 8—9} times in the length of head, inter- 
orbital width 3 times, length of snout 1} times. Interoperculum with 6-10 spines. 
23 scutes in a longitudinal series, 5 between dorsal and adipose fin, 9-10 between anal 
and caudal. D. I 8, the first ray equal to }-# the length of head, the last } as long; 
length of base of dorsal little less than its distance from the caudal. A.I4. Pectoral 
spine extending a little beyond the base of ventral. Caudal slightly emarginate. 
Yellowish brown, with little light spots on the head; fins without spots, sometimes a 
dark streak on each side of the dorsal rays; tips of the caudal lobes light reddish. 
The typical examples, from Callacate, Peru, measure up to 135 mm. in total length. 
12. CHa&TosToMuS ANOMALUS. (Plate XIII. fig. 2.) 
Chetostomus anomalus Regan, Ann. Mag. Nat. Hist. (7) xi. 1903, p. 599. 
Depth of body about 6 times in the total length, length of head about 3 times. 
Head as broad as long and 2-2} times as long as deep. Diameter of eye 8-12 times 
in the length of head, interorbital width about 3} times, length of snout about 12 
times. Length of mandibular ramus a little greater than the interorbital width. 
Interoperculum armed with 6-10 short spines. 24-26 scutes in a longitudinal series, 
10-12 between anal and caudal. D.I 8 (rarely 1 7 or I 9), the first ray equal to 3-} 
the length of head, the last # as long; length of base of dorsal equal to 3—} its distance 
from the caudal. A. I 3-4 (exceptionally I 2), Adipose fin small, rudimentary or 
absent. Pectoral spine scarcely reaching origin of ventral. Caudal peduncle 2-2} 
times as long as deep. Olive-brown, with rather large light spots on head and usually 
on body; fins blackish, sometimes with rows of light spots or alternate light and dark 
cross-bars, a black spot at the base of first interradial membrane of the dorsal. 
‘Total length 160 mm. 
Merida, Venezuela, and mountain-streams above it. 
Of 235 examples, 14 have a well-developed adipose fin, in 42 it is very small, in 78 
more or less rudimentary, and in 101 wanting. In these last, however, a small, flat, 
median plate represents the keeled scute which usually supports the spine of the 
adipose fin. 15 examples have I 7 dorsal rays and 23 have 19. 2 have I 2 anal rays 
and 47 have I 3. 
13. CHaTosromus THoMSoNI, sp. n. (Plate XIV. fig. 2.) 
Depth of body 63-7 times in the total length, length of head 3 times. Head as broad 
as long and 2} times as long as deep. Diameter of eye 7-9 times in the length of 
head, interorbital width 83-33 times, length of snout about 13 times. Length of 
mandibular ramus equal to or a little greater than the interorbital width. Inter- 
