Cope.] '^^ [.Tan. 5, 



cies, C. interruptus Jen., is said to have 11 dorsal rays and no maxillary 

 teeth. 



DiAPOMA SPEOULTFERUM, Amev. NattLvalist, 1894, p. 67. 



Char. gen. — Adipose fin present. Dentition as in Tetragonopterus, i. e., 

 with two rows of denticulate teeth on the premaxillary bone and one row 

 on the dentaries. Origin of the short dorsal fin entirely posterior to that 

 of the ventrals. Anal fin elongate. Belly not keeled. The operculum 

 produced posteriorly below tiie lateral line to an apex. Lateral line not 

 complete. Narcs close together. Inferior limb of external branchial 

 arch without rakers. 



Tliis genus is allied to Hemigrammus, but has a peculiarly formed oper- 

 culum, wliich displays, a tendency towards the character which is so 

 much developed in Corynopoma Gill.* 



Char specif. — Form rather elongate, the depth entering the length 3.25 

 times (less caudal fin). Length of head entering the same 3 6 times. 

 Maxillary bone elongate, reaching the line of the anterior border of the 

 pupil, supporting 4-5 teeth at its proximal end. Eye large, its diameter 

 exceeding the length of the muzzle, equaling interorbital width, and 

 entering length of head three times, one diameter equaling the long hori- 

 zontal diameter of the operculum and suboperculum. The latter two 

 elements form a sublriangular plate, of which the long diameter is hori- 

 zontal, and of which the base is continued as a process along the posterior 

 border ot the preoperculum. The apex of the triangle is formed by the 



4_ 



extremity of the suboperculum, and is obtuse. Scales, 37 ; lateral line 



5 

 pores and tubes present on ten scales behind the epiclavicle, and on eight 

 scales anterior to the caudal fin. Radii, D. 1.9; A. 2.29; V. 7 ; P. 11. 

 Pectorals just reaching ventrals, and ventrals not reaching anal. Caudal 

 deeply emarginate, a curved patch of scales extending on the inferior 

 lobe from the base. Anal fin with its free border concave, the anterior 

 rays longer than the posterior, and the posterior longer than the middle 

 rays. 



Sides, excepting the dorsal portion and that part adjacent to the anal 

 fin, with a mercury-like metallic surface ; the operculum most brilliantly 

 refulgent, the cheeks little less so. A straight leaden line from the head 

 to tiie base of the caudal fin. No spots. 



Total length, 45 mm.; length to base of caudal fin, 36 mm.; length to 

 base of anal, 22 mm.; length to base of ventrals, 17 mm.; length of head. 

 10 mm.; length of head to preoperculum, 6 mm. 



But one specimen of this curious little fish was sent by Mr. Smith. It 

 is the most brilliant of the CharacinidcC known to me. 



♦This genus received several names from Prof. Gill at the same time. Of these, Dr. 

 Giintlier selected Corynopoma, as he had a right to do, and he has been followed in this 

 by most otlier ichthyologists. One of the other names cannot therefore be now selected 

 for this genus because it was printed on a previous page, as has been recently proposed . 



