4:22 A Revision of the 



12. CIJBITaA.TUS BIOTACUIiATUS. 



Curimatus bimaculatus Steindachner, '76a, 38 (Hyavary). 



Habitat, Amazon, Solimoens. 



Many specimens from Hyavary and Coary, Villa Bella, 19a; the 

 largest .17 m. 



This species can readily be distinguished by its color-markings. 



Compressed, ventral outline nearly straight to the anal, back greatly 

 arched. Preventral region broad and flat, without distinct lateral 

 keels; post ventral region rounded, with three indistinct keels. Pre- 

 dorsal region with a prominent median keel; postdorsal region 

 rounded. 



Scales thin, persistent, pectinate or serrate. Caudal naked. 



Profile slightly depressed at the occiput, more or less strongly arched 

 behind it. Eye 1 in snout, 3^ in head, 1^ in interorbital. 



Mouth inferior, head depressed. 



Air-bladder extending to anal. 



Caudal broad and deeply emarginate. Anal high, emarginate; some 

 of the anterior rays extending past origin of caudal. Ventrals reach- 

 ing to or past the vent; pectorals not to ventrals. 



Bluish above, silvery on sides and below. A blackish spot at base of 

 middle caudal rays, another at base of middle dorsal rays, usually an- 

 other spot on the back just in front of the dorsal fin; an opaque 

 whitish spot at the base of each caudal lobe. 



Head 4; depth 2f-3i. D. 13-13; A. 11. Scales 8-44 to 47-5. 



12a. CURIMEATUS BIITIACUL ATUS SIALIS Tar. nov. 



Types, No. 20,308, nine specimens, .09-. 19 m. Manacapuru; W. 

 James. 



This variety differs from the typical bimaculatus in having the 

 dorsal and caudal spots very faint, or more often they are not pres- 

 ent. A straight, or more usually a dumb-bell-shaped, brown spot at 

 base of caudal. Those with a straight caudal spot have the predorsal 

 region plain; those with a dumb-bell-shaped spot hav^e a blackish spot in 

 front of dorsal and another behind the occipital process, and have the 

 scales more pectinate than the other specimens. Scales 8-48 to 53-6. 



12b. CURIOTATUS BIOTACUIi ATUS TRACHYSTJETBEUS. 



Curimatus trachystethiis Cope, '78a, 684 (Peruvian Amazon). 



Habitat, Amazons from Serpa to Peru. 



Our specimens differ from those described by Dr. Cope, in having a 

 distinct, though low, postventral keel. Serpa; Fonteboa; Tabatinga. 



Ventral outline somewhat more arched than in bimaculatus. 



Scales serrate or crenate. 



Pectorals in one specimen reaching ventrals. 



Color as in bimaculatus, without the caudal spot. A blackish spot 

 behind tip of occipital process. Scales 8-48 to 53-6 to 7. 



