FISHES OF THE FAMILY LOEICAEIID^E. 253 



a. First dorsal ray f-f the length of head. 

 Interorbital width 2^-23- times in the length of head ; last dorsal 



ray, when laid back, reaching spine of adipose fin ; caudal 



peduncle 2§-2f times as long as deep 6. X cirrhosa C. & V. 



Interorbital width 2^ times in the length of head ; last dorsal ray, 



when laid back, not reaching spine of adipose fin ; caudal 



peduncle 2£ times as long as deep 7. X. chagresi Eigm. 



yS. First dorsal ray -|-|- the length of head. 

 Interorbital width 2| times in the length of head; last dorsal ray, 

 when laid back, reaching spine of adipose fin ; caudal peduncle 

 2|-2| times as long as deep 8. X occidentaiis Rgn. 



c. Length of mandibular ramus 2-2-^ times in the interorbital width. Length of base 



of dorsal equal to its distance from spine of adipose fin, which is not reached by the 

 last ray, when the latter is laid back. 

 Diameter of eye 7h times in the length of head, interorbital width 



2|j- times, length of snout twice (in a specimen of 100 mm.) . 9. X. brevipinnis Rgn. 

 Diameter of eye 10 times in the length of head, interorbital width 



3 times, length of snout 15 times (in a specimen of 100 mm.) . 10. X. montana Rgn. 



d. Length of mandibular ramus 1^-lf times in the interorbital width. Length of base 



of dorsal equal to its distance from spine of adipose fin, which is not reached by the 

 last ray, when the latter is laid back. 

 Interoperculum armed with 12-16 spines ; pectoral spine extending 



to base of ventral 11. X. bufonia C. & V. 



Interoperculum armed with 20-30 spines ; pectoral spine extending 



to, or nearly to middle of ventral 12. X stigmatica Eigm. 



1. Xenocaea latifeons. (Plate XV. fig. 1.) 

 Chatostomus latifrons Giinth. Proc. Zool. Soc. 1869, p. 426. 



Depth of body 5 times in the total length, length of head 2f times. Head 1\ times 

 as long as broad and If times as long as deep. Diameter of eye 6^ times in the length 

 of head, interorbital width 2^ times, length of snout If times. Length of mandibular 

 ramus 3-j times in the interorbital width. Snout with a broad naked margin, without 

 tentacles; interoperculum armed with 13-15 spines, the longest equal to f- the length 

 of head. Posterior scutes rather strongly spinate ; none of the scutes carinate ; 

 24 scutes in a longitudinal series, 6 between dorsal and adipose fin, 11 between anal 

 and caudal. D. I 8, the first ray equal to f- the length, of head ; length of base of 

 dorsal a little less than its distance from the caudal. A. I 4. Pectoral spine 

 extending to middle of ventral. Caudal peduncle 2\ times as long as deep, 

 Olivaceous ; a black spot at the base of the first interradial membrane of the dorsal. 



Total length 160 mm. 



One specimen from the Peruvian Amazon. 



