412 Memoir Sears Foundation for Marine Research 



lb. Sides without silvery band; origin of dorsal definitely behind insertion of pelvic 

 fin and about equidistant between margin of snout and base of caudal ; teeth miss- 

 ing on maxillary and premaxillary; dorsal with 14 or 15 rays; anal with 15—17 

 rays; scales 35—38. 



2a. Greatest depth of body 3.5—4.0 in SL (75- and 40-mm specimens, re- 

 spectively); depth of caudal peduncle close to half of greatest depth of body; 

 head 4.0 in SL; snout 4.0 in head; base of dorsal fin about as long as its 

 longest rays. amazonica (Steindachner) 1879, below. 



2b. Greatest depth of body 3.1—3.4 (60— 68-mm specimens) in SL; depth of cau- 

 dal peduncle definitely less than half of greatest depth of body; head 4.25—5.1 

 in SL; snout 4.6—5.5 in head; base of dorsal fin notably shorter than its longest 

 rays. serrata Eigenmann 1912, p. 413. 



Rhinosardinia amazonica (Steindachner) 1879 



Study Material. None. 



Distinctive Characters. This species is closely related to serrata. However, 

 amazonica differs from serrata, according to the original description, in the some- 

 what more slender body, slightly larger head, longer snout, the proportionately deeper 

 caudal peduncle, in the absence of teeth on the mandible, and in the somewhat dif- 

 ferent proportion of the longest dorsal rays with respect to the head length and 

 dorsal base. 



Description. Proportional dimensions in per cent of standard length, and counts, 

 modified after the original description by Steindachner (see Synonyms and Ref- 

 erences). 



Body: depth 27.5 in 75-mm examples, Scales: 37. 



about 25 in those 40 mm long. Ventral scutes: 27. 



Head: length 25. Fin rays: dorsal 15; anal 16. 



Body strongly compressed, its ventral outline notably more strongly convex than 

 dorsal outline, its greatest depth ■t,.^ in SL in large examples, 4.0 in smaller ones. Cau- 

 dal PEDUNCLE deep in comparison with depth of body, close to half of greatest depth. 



Scales adherent; about 37 in a horizontal row between margin of opercle and base 

 of caudal ; a vertical groove dividing the free (exposed) part of scale from the covered 

 part, 2 or 3 sharp grooves on the former. Ventral scutes on chest and abdomen, i 5 

 in front of pelvic fins and 1 2 behind them. 



Head 4.0 in SL. Snout 4.0 in head. Eye 3.0. Mouth small. Maxillary reaching 

 little beyond anterior margin of eye. Mandible projecting little. Teeth absent on pre- 

 maxillary, mandible, and vomer. 



Dorsal fin with base about as long as longest rays, its origin a little behind vertical 

 at insertion of pelvic, and equidistant between end of head (snout) and base of caudal. 



