1903.] NATURAL SCIENCES OF PHILADELPHIA. 519 



Pectorals reaching beyond the base of the ventrals. 



Ventrals reaching beyond the origin of the anal. 



Anal moderately high its entire length, its last ray li in the fourth 

 ray, which ecjuals the diameter of the eye. 



Color: Top of head dusky. A deep A^-shaped humeral spot. 

 Dorsal almost black. The middle caudal rays black. The last five 

 anal rays and the distal f of the other rays Ijlack. The tips of the ven- 

 trals dusky. There is no caudal spot or lateral band. 



In some of the co-types the tips and bases of the dorsal rays are 

 white, the black band of the anal is narrower and the outer caudal 

 rays are pigmented. ^ ,4^ 



Related to unilineatus (Gill) and elegans Steind. 



The following table of measurements shows the variations among 



the seven specimens: 



Min. Max. Average. 



Length in mm 29.0 37.0 34.2 



Dorsal 10.0 11.0 



Anal 27.0 28.0 



Depth 2.6 3.0 



Head 3.2 3.6 



Eye 2.4 2.5 



Scales 6.5 to 7.5-33 to 34-5.5 to 6.5. 



64. Hemigrammus lutkeni Boulenger. 



Tetragonoptenis rivularis interrupta Liitken. Velhas Flodens Fiske, XIII, 

 215, 1875 (preoccupied b}^ Tetraganopterus interruptus J enyns=C heir odon 

 interruptus) . 



Tetragonopteriis lutkenii Boulenger, Ann. and Mag. Nat. Hist,, 1SS7 (Rio 

 Grande do Sul). 



Sixteen alcoholic specimens (29), the largest 35 mm. Estancia la 

 Armonia. 



Straw colored, a vertical humeral spot, a distinct caudal spot con- 

 tinued to the ends of the middle caudal rays, gradually narrowed and 

 continued forward as a dark lateral band or line sometimes to the 

 humeral spot, more frequently not so far. 



Lateral line of the left side developed on 13, 24, 10, 13, 29, 11, 21, 

 10, 11, 25, 15, 10 (average 16) scales in as many individuals. In those 

 with the longest lateral line some of the scales are simply notched, 

 without a developed tube. 



A large number of formalin specimens from Pypucu (219) and a 

 few from Arroyo Trementina (253) differ from the above in that the 

 dark lateral band or line abruptly joins the caudal spot, appearing as 

 a marking independent from that spot, while in the specimens from La 

 Armonia it seems to be a direct continuation of that spot. They are 



