262 



U. 8. P. R R. EXP. AND SURVEYS ZOOLOGY — GENERAL REPORT. 



The general ap])earance is the same as that of the preceding species. The snout is more conical, 

 the mouth larger and more deeply cleft. The head constitutes likewise the fifth of the total 

 length, which measures three inches and a half. The eye is well developed, sub-circular ; its 

 diameter entering a little over three times in the length of the side of the head. 



The anal fin is deeper than long, its anterior margin being nearer the tip of the lower lobe of 

 the caudal than the extremity of the snout. The dorsal is higher than in the preceding species. 

 The pectorals being slender. The formula of the fins reads thus : 



D 2, 8 + 1 ; A 2, 8 + 1 ; C fi, 1, 9, 8, 1, 7 ; V 1, 8 ; P 15. 



The scales are large, deeper than long, sub-elliptical on the back, elsewhere anteriorly 

 sub truncated and posteriorly rounded, with radiating grooves upon the posterior section only. 

 There are but nine rows of scales, five above and three below the lateral line. 



The color is reddish brown, lighter beneath than above ; the middle of the flanks appearing 

 as though streaked with silver ; the fins being unicolor, of a light yellow or straw tint. 



Eeferences to the Jigures. — Plate LVII, fig. 1, represents Alburnops shumardi, size of life. 

 Fig. 2, a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, a scale 

 from the abdominal region. 



List of specimens. 



3. ALBURNOPS ILLECEBR0SU8, Grd. 

 Plate LVII, Figs. 5—8. 



Spkc. Char. — Head contained five times and a half in the total length. Snout sub-conieal ; lower jaw shorter than the upper 

 Posterior extremity of maxillar bone extending to a vertical line drawn in front of the orbit. Anterior margin of dorsal fin 

 equidistant between the extremity of the snout and the insertion of the caudal. Insertion of ventrals situated somewhat in 

 advance of the anterior edge of the dorsal ; their tips reaching the vent. Reddish brown, lighter beneath than above, with the 

 middle of the flanks silvery ; fins unicolor. 



Syn. — Albumopa iUectbrosua, Grd. in Proc. Acad. Nat. So. Philad. VIII, 1856, 194. 



This is perhaps the most graceful of the three species so far known of this genus. The snout 

 is less prominent than in A. shumardi, and more so than in A. hlennius. The eyes are larger 

 than in either of the two s])ecies just alluded to ; their diameter entering about three times in 

 the length of the side of the head. The head is contained five times and a half in the total 

 length, which averages about three inches. 



The dorsal fin is much higher than long, and not well represented on the accompanying 

 figure : it being much lower posteriorly, hence its upper edge a good deal more inclined 

 backwards. The anal is, as usual, deeper than long ; its anterior margin being equidistant 

 between the isthmus and the tip of the inferior lobe of the caudal. 



The scales are large, much deeper than long, and jiroportionally more so than in the fore- 

 going two species. Their anterior margin is sub-truncated, the posterior edge being rounded, 

 with radiating grooves upon the latter section only. There are ten rows of scales as in A. 

 hlennius. 



