4 1 6 Memoir Sears Foundation for Marine Research 



equals Pristigaster flavifinnis Valenciennes {in d'Orbigny), Voyage Amer. Merid., Poiss., 5(2), 1847: 

 8; Atlas, d'Orbigny, 1839: pi. 10, fig. 2. 



Zunasia Jordan and Metz, Mem. Carneg. Mus., 6, 191 3: 7; type species by monotj'py, Pristigaster chinensis 

 Basilewsky equals Alosa elongata Bennett. 



Pseudochirocentndon Miranda-Ribeiro, Publ. Comm. Linhas Telegr. Estrat. Matto Grosso Araazonas, 58, 1923 

 ("1920"): 8; type species by monotypy, P . amazonicum Miranda-Ribeiro. 



Neosteus Norman, Ann. Mag. nat. Hist., (9) 11, 17, 1923: type species Pellona ditchela Valenciennes by sub- 

 sequent designation of Norman, Zool. Rec, Pisces, for 1923: 25. 



Characters. Body elongate, rather strongly compressed, Its ventral outline more 

 strongly convex than dorsal outline. Bony scutes strong, about 25—37 along sharp edge 

 on chest and abdomen. Scales small to rather large, often missing on preserved 

 specimens, generally with several irregular vertical grooves. Snout with or without 

 a definite median notch. Mouth moderate, strongly oblique. Mandible projecting 

 strongly. Maxillary generally reaching under anterior half of eye, with a bone or liga- 

 ment between it and premaxillary. Teeth all small, present in a single series on anterior 

 part of mandible, on premaxillaries, maxillaries, and usually in bands on palatines, 

 pterygoids, and tongue, but none on vomer. Gill rakers strong, serrate, about 12—25 

 on lower limb of first arch (in American species). Dorsal fin with about 15—20 rays 

 (in American species). Anal fin long, its origin under posterior rays of dorsal or just 

 behind that fin, with about 36—52 rays (in American species). Pelvic fin small (occa- 

 sionally absent in one species), with 6 or 7 rays (in American species). 



Remarks. This genus is characterized by the elongated, compressed body with a 

 strongly convex ventral outline, by the very long anal fin, and by the small pelvic fin, 

 inserted in advance of the dorsal fin and consisting of only 6 or 7 rays. Furthermore, 

 the premaxillary and maxillary are not adjoined, a soft ligament (in Ilishci) or a bone 

 (in Neosteus) being present between them.^" 



Range. Tropical parts of the Atlantic, Indian, and Pacific oceans. Fresh waters of 

 the Amazon Basin. One species, I.narragansetae, reported from Rhode Island. 



Key to Species of the Western Atlantic and 

 Tributary Rivers 



I a. Ventral scutes 20—25 before and 10—14 behind pelvic fins, total number 32—37. 

 2a. Gill rakers only 12 or 13 on lower limb; scales 72— 75 in a lateral series; depth 

 of body less than a third (27.5-30 "/o) of SL. 



altamazonica Cope 1872, p. 417. 

 2 b. Gill rakers 23—3 i on lower limb; scales fewer than 70 in a lateral series; depth 

 of body about equal to a third (30—37 "/o) of SL. 



3a. Dorsal fin with 19 or 20 rays; gill rakers on lower limb 23—26; axillary 

 process of pectoral reaching middle of first ray. 



castelnaeana (Cuvier and Valenciennes) 1847, p. 419. 



50. See Myers (97: 63) for discussion. 



