376 MEMOIRS OF THE CARNEGIE MUSEUM 



angle; dentition as in Tetragonopterus, premaxillary with an inner series of about 

 five teeth, whose denticles are in a crescent, and an outer series of four or more 

 teeth, the second or third withdrawn from the line of the rest; dentary with four 

 large teeth, abruptly followed by minute teeth on the side; maxillary slender, with 

 as many as three teeth on its upper angle, these scarcely evident in small specimens. 



Gill-rakers long, slender, 10 + 16. 



Scales regularly imbricated, except over the anal musculature, each scale with a 

 few radiating striae; lateral line but slightly decurved; anal with a sheath of two 

 rows of scales, which are continuous with those of the sides; caudal lobes with 

 minute scales for more than half their length. 



Dorsal pointed, the highest ray in the young reaching the adipose, shorter 

 in the adult; adipose large; caudal forked, anal emarginate, more so in young than 

 in adult; ventrals reaching to, or a little beyond, the origin of the anal, pectorals to 

 above the middle of the ventrals. 



Highly iridescent, silvery; a silvery lateral band; two vertical humeral bars, 

 the second merging into the pigmentation of the sides; outer margin of ventrals 

 and anterior margin of anal frequently black; fins variously peppered. 



The specimens from Erukin differ from the rest as follows: the dorsal and anal 

 are falcate, the longest dorsal rays reaching beyond the origin of the adipose, the 

 longest anal ray to the base of the twenty-fifth ray. 



Subfamily Chalcinin^. 



Chalcinus Cuvier and Valenciennes. 



Chalceus MtJLLER and Troschel, Horse Ichth., I, 1845, 15 {angulalus), not of 



Cuvier and Valenciennes. 

 Chalcinus Cuvier and Valenciennes, Hist. Nat. Poiss., XXII, 1848, 258 {brachy- 



pomus) . 

 Triportheus Cope, Proc. Acad. Nat. Sci. Phila., 1871, 264, pi. 8, fig. 3, and pi. 14, 



fig. 1 (flavus). 

 Coscinoxyron Fowler, Proc. Acad. Nat. Sci. Phila., 1906, 450 (culter). 



Type, Chalcinus hrachypomus Cuvier and Valenciennes. 



Compressed, large-scaled, herring-like fishes; lateral line decurved; prevcntral 

 edge compressed; pectoral large; mouth small, a pair of conical teeth in the lower 

 jaw behind a series of lobed teeth; upper jaw with two series of teeth; caudal 

 emarginate, the middle rays prolonged. 



The species and varieties, about thirteen in number, differ from each other 

 but slightly. Within our limits one species is found about Morawhanna, another 

 in the Essequibo and Demerara. They may be distinguished as follows: 



