SOUTH AMERICAN NEMATOGNATHI. 157 



nearer snout than to the anal fin. Base of adipose fin 

 3-4 in the length; its distance from the dorsal f its own 

 length. 



Caudal deeply forked, the lobes pointed, the upper 

 lobe J longer than the lower, about 4 in the length. 



Anal convex, the longest ray lf-2 in head. 



Ventrals If in head; scarcely reaching more than half 

 way to the anal, inserted a little behind the vertical from 

 the last dorsal ray. 



Pectoral spine strong, unusually strong and sharp 

 retrorse hooks along the inner margin; the outer margin 

 roughened. The pectoral fin reaches to somewhere be- 

 low the anterior half of the dorsal, not nearly to the 

 ventrals. 



Color light brown, a dark lateral band (obsolete in 

 some specimens); fins with dark punctulations at their 

 tips; the adipose fin narrowly margined with dusky. 

 Dorsal and anal fins with the membrane thickened at the 

 base, hyaline above. 



Head 4-5; depth 6J-7; depth of caudal peduncle 2-2f 

 in head. D. I, 6; A. 12. 



The three specimens from Obidos and those from Iga, 

 about eighty in number, are all very small, about .06 m. 

 long. There is a trace of a lateral band, below which 

 there is a broader silvery band. At the humeral re- 

 gion the abdominal wall is transparent. There are in 

 some of these specimens traces of a dark line along 

 the side of the head. They differ from specimens of 

 vittata of the same size in the size of the eye, the slope 

 of the head, the serration of the pectoral spine and the 

 slenderness of the body. The pectoral spine with 

 straight teeth along the anterior margin to near the tip; 

 in the smallest specimens of lateristriga the serration on 

 the anterior margin of the pectoral spine is entirely 

 obliterated near the base and greatly reduced all along. 



