40 



INDIANA UNIVERSITY 



5221 C. M. 23 males, the largest 70 mm., over 100 females, the largest (><S 



mm. Cacheoira, Rio .Tacuhy. Jan. 20, 1900. Haseman. 



It is not certain that the specimens before me all belong to the species 

 figured by Steindachner and Perngia. Both figure the dorsal and the anal 

 as synnnetrical. one gives the anal as 42, the other as 32. Neither saw the 

 double lobing of tlie anal, nor the divided caudal, nor the glandular pouch 

 on the caudal. There is, however, no doubt al)Out the generic identification, 

 and Perugia noticed the black caudal tips. 



Head 4.25; dei)th 2.5-2.75; D. 10; A. 3.2^ 3^4^ _3.e^ 

 scales 7-41 to 43-0 ; eye 3-3J in the head, 1.25 in interorbital ; depth of 

 caudal peduncle e<iual to its length. 



( Vmipressed ; ventral profile much more strongly curved than the dor- 

 sal; ])rofile from snout to dorsal nearly straight, angulated at the origin 

 of the dorsal; entire ventral surface comjjrcssed. knife-like, without scales 

 across the median line except near the isthnms ; predorsal area rounded, 

 without a median series of scales ; occiin'tal process very short, skull con- 

 vex, with longitudinal grooves above the eye; frontal fontanel very short 

 and narr()^^^ parietal club-shaped ; second suborl)ital covering the entire 

 cheek; mouth large, very obli(iue. maxillary-premaxillary border little less 

 than half the length of the head; mandible with six graduated teeth (the 

 second below the normal in size) and several minute ones on the sides; 

 in'emaxillary with an outer series of three teeth and an inner series of six 

 or seven; maxillary with one to seven teeth. All the larger teeth with a 

 strong median cusp and two lateral cusps. 



Origin of dorsal about e^pudistant from base of middle caudal rays 

 and upper angle of gill-openings, the margin truncate in the female, the 

 end of the rays subequal. the anterior four (beyond the rudimentary one) 

 in the male variously prolonged, reaching to the middle of the caudal in 

 extreme cases. Caudal lobes similar in the two sexes, the fin split to its 

 base at the middle in the male, base of the rays just above the divide 

 tumid a cavity at the base of the rays just below the middle arched over 

 by connected scales, the cavity open behind, the opening guarded by a leaf- 

 like scale above and a firm, narrow scale curved so as to form the lower 

 border and also the posterior border ; anal simply emarginate in the 

 female and younger males, three-lobed in the mature males, the anterior 

 lobe consisting of 7-10 narrow rays se])arated by wide membranes, the 

 second to fcmrth ray highest, reaching beyond tip of last in extreme cases, 

 the second lobe consisting of 4-7 rays bearing retrorse hooks along the 

 ])Osterior lateral face, the rays broader, the membrane narrower than on 

 the first lobe, the remainder of the fin as in the female; ventrals short, 

 not reaching anal ; pectorals about to tips of ventrals in the" female, to the 

 anal in the male. 



Lateral line eomi)lete. but little decurved; axillary scales small, 

 caudal naked excei>t as stated above for the males; scales with several 

 radials, regularly imlnlcate exceii't over and a little in front of where the 

 rows are defiected to^A■ard the anal and continued as a sheath of about 

 three rows along the -base of the anal but not attached to the fin. 



Silvery ; prolonged dorsal rays dusky ; ti])s of caudal lobesi with short 

 oblique or brown Itars: rays of anterior lobe of the anal of the male fre- 

 quently black tipped; tips of pectorals in the male usually black. 



