THE AMERICAN TETRAGONOPTERINAE. 



269 



Very abundant in the Magdalena from the coast as far as Honda or Girar- 

 dot at least. It was not taken in the upper (3000 feet) part of the Cauca. 



There is very little difference between A. atratoensis and A. caucanus; the 

 latter is a little more slender on an average, and the head is comparatively a 

 little shorter. The two species can very readily be distinguished at sight. It 

 is very probable that A. caucanus should be placed in the synonymy of A. stilbe; 

 they differ in the development of the second suborbital. 



Head 4^.33; depth 2.33-3, average 2.7; D. 11; A. ^, -V^, ff, -\»-, 4f, V-; 



scales 7 or 8- 



3 6 3 7 



3R 39 40 41 42 7 „„ Q 



TT) s-) "5"i "3"j ~Tr~ I or s. 



29. AsTYANAX (Zygogaster) filiferus (Eigenmann). 

 Plate 51, fig. 2. 



Zygogaster fiKferus Eigenmann, Indiana univ. studies, 1913, no. 18, p. 23 (Apulo). 



Habitat. — Central portion of Magdalena Basin. 



Specimens examined. 



Astyanax caucanus seems to shade into this species at Apulo. All the 

 specimens were preserved in formalin so a direct comparison with the alcoholic 

 material from the Magdalena is not altogether satisfactory. 



Males of S. filiferus are imdoubtedly more slender than males of A. caucanus. 

 The origin of the anal is nearer to the origin of the dorsal than to the base of the 

 last anal ray. The depth in the males is 3 in the length, the depth in the females 

 averages 2.5. 



A. 38 or 39; scales in the lateral line 38 or 39. 



The outer rays of the ventrals and the first dorsal ray are prolonged, filiform. 



specimen. 



