SOUTH AMERICAN NEMATOGNATHI. 307 



the mouth. Length of the snout 

 greater than interocular width. Cleft 

 of the mouth 2J in the head. Teeth 

 as in A. valenciennesij the depth of 

 intermaxillary band in front equal to 

 a diameter of the eye. 



Gill-membranes confluent with the skin of the isthmus 

 behind the eyes. Gill-rakers 5+12. Pectoral pore small. 



Lateral line zig-zag, branching. 



Distance of dorsal spine from the snout 3|-3|- in the 

 length; the spine 2 2-J- in the head, slender, flexible, 

 with small teeth on both margins. Distance between 

 dorsal and adipose fins not quite 2 in the length; adipose 

 fin high and short, half as long as the dorsal fin. 



Caudal deeply forked, the lobes pointed, 4| in the 

 length. Origin of the anal fin equidistant between base 

 of caudal fin and the rictus, or the posterior margin of 

 the eye. 



Veiitrals reaching the anal, 2 in head. 



Pectoral spine smooth on its outer margin except near 

 base, its inner margin serrate, much more slender than 

 in dentatus, 2 in the head. 



Dorsal surface very dark blue, becoming abruptly pale 

 011 the sides; base of caudal fin dusky; fins otherwise 

 pale. 



Head 3|-4; depth, below dorsal, 7J-8; above anal 5|; 

 Br. 11; D. I, 6; A. 43. 



Four specimens .26 m. long. Para. Agassiz & Bourget. 



242, Ageneiosus dentatus, 



Ayciiciosus dentatvs Kner, SB. Ak. Wien, xxvi, 441, 1857 (Surinam); 

 Giinther, Cat. Fish. Brit. Mus. v, 192, 1864 (Para). 



Ageiif/oti/ts /xirdalis Liitken, Vidensk. Meded. 190, 1874 (Caraccas); 

 Steiudachiier, Fiscli-faunn Magd. Strornes. 17, pi. iii, figs. 1-1 a, 

 1878 (Magdalen Kiver); Steindachiier, Fiseh-fauna des Cauca and 

 Fliisse bei Guayaquil, 10, 1879 (Cauca); Eigenm. & Eigenui. 

 Proc. Cal. Acad,2d Ser. i, 150, 1888 (Tefiv; Para; Cameta). 



Habitat: Amazon; Solimoeiis from Para to Teffe north to Guiana 

 an 1 lti'> Ma'daleiia. 



