FISHES OF THE FAMILY LOEICAEIID^E. 255 



Interoperculum armed with 10-12 spines, the longest | the length of head. 

 23-24 scutes in a longitudinal series, 6-7 between dorsal and adipose fin, 11 between 

 anal and caudal. D. I 7, the first ray f— § the length of head, the last ray, when laid 

 back, reaching the spine of the adipose fin or the scute preceding it ; length of base 

 of dorsal equal to its distance from posterior 4; of spine of adipose fin. A. I 4. 

 Pectoral spine extending to anterior ^ of ventral. Caudal obliquely truncate, 

 the lowest ray f-f the length of head. Caudal peduncle 2-^-2f times as long 

 as deep. Brownish; head and anterior part of body with light spots which are 

 separated by a network of dark lines ; fins dusky, the dorsal with darker undulating 

 cross-bars. 



Total length 125 mm. 



Four specimens : Guiana. 



5. Xenocaba hoplogents. 



Chcetostomus hopl.ogenys Giinth. Cat. Fish. v. p. 217 (1864). 



Cfuetostomus leucosticlus Gttnth. t. c. p. 248.' 



Chatostomus alga Cope, Proc. Ac. Philad. 1871, p. 287, pi. xv. fig. 3. 



Chcetostomus malacops Cope, t. e. p. 287, pi. v. fig. 2. 



Chatostomus tectirostris Cope, t. c. p. 288, pi. xv. fig. 2. 



Ancistrus hoplogenys Eigenm. & Eigenm. Proc. Cal. Ac. (2) ii. 1889, p. 48, and Occ. Pap. Cal. Ac. 



i. 1890, p. 448. 

 Ancistrus leucostictus Eigenm. & Eigenm. 1. c. and t. c. p. 447. 



Depth of body about 5 times in the total length, length of head 2f-2£ times. 

 Head 1-g — 1-g- times as long as broad and twice as long as deep. Diameter of eye 

 5-G-|- times in the length of head, interorbital width 2-24; times, length of snout 

 1J-2 times. Length of mandibular ramus 3|— 3|- times in the interorbital width. 

 Snout with tentacles. Interoperculum armed with 7-10 spines, the longest ^—4 the 

 length of head. 23-24 scutes in a longitudinal series, 7 between dorsal and adipose 

 fin, 10-11 between anal and caudal. D. I 7, the first ray f— | the length of head, 

 the last ray, when laid back, reaching the spine of the adipose fin ; length of base of 

 dorsal equal to its distance from posterior \ or tip of spine of adipose fin. A. I 4. 

 Pectoral spine extending to base (young) or anterior 4 (adult) of ventral. Caudal 

 obliquely truncate, the lowest ray nearly (adult) or quite (young) as long as the 

 head. Caudal peduncle 24-2f times as long as deep. Brownish ; fins dusky ; 

 small white dots on head, body, and fins, which are fewer and better defined in the 

 young ; dorsal with a blackish spot at the base of the first interradial membrane. 



Total length 145 mm. 



Eight specimens : Guiana ; R. Amazon ; It. Paraguay. 



vol. xvn. — pabt in. No. 9. — October, 1904. 2 m 



