THE AMERICAN TETRAGONOPTERINAE. 265 



towards the anal; a few diverging radials. Lateral line decurved; a row of 

 scales along the base of the anterior part of the anal. 



A conspicuous round humeral spot over the third and fourth scales of the 

 lateral line; a spot at the'base of the caudal. 



This species is abundant in the Atrato in which the following number of 

 scales were observed in the lateral line: ^, fr, V and the following number 

 of anal rays -^f , -^f , ^, ¥, ¥• 



The outer ventral rays in the male are sometimes filiform and the anal is 

 sometimes distmctly falcate, the third and fourth rays forming a narrow lobe, 

 the fifth to eighth rays decreasing rapidly in height. 



This species is replaced by A. caucanus in the Magdalena Basin, which 

 differs only in having the second suborbital in contact with the lower limb of 

 the preopercle along the entire length. 



26. AsTYANAX (Zygogaster) magdalenae Eigenmann and Henn. 



Aslyanax magdalenae Eigenmann & Henn, Ann. Carnegie mus., 1914, 7, p. 89. 



Habitat. — Magdalena Basin near Girardot. 

 I Specimens examined. 



Closely related to A. stilbe (Cope) differing in the greater depth, the shorter 

 anal, and the lack of a median series of pre ventral scales. 



Head 3.5-3.8; depth 2.33; D. 11; A. 33-34; scales 8-36 or 37-7 (to 

 ventrals), snout 1.3 in eye, 4-4.5 in head; eye 3-3.3 in head and equal to inter- 

 orbital. 



Dorsal and ventral profiles equally and strongly arched. Predorsal area 

 without a median series of scales, those of the two sides overlapping, an occa- 

 sional' median scale neai' the origin of the dorsal. Preventral area keeled, scales 

 of the two sides apposed in the mid-line. 



Interorbital convex, smooth; occipital process elongate, sharp, about 

 one fourth of the distance from its base to the dorsal, bordered by three large 

 scales. Frontal fontanel bluntly triangular, as wide as the parietal and about 

 two thirds as long as the parietal without the occipital groove. Second and 



