FISHES OF WEST COAST OF PERU. 89 



Genus ISACIA Jordan and Fesler. 

 118. ISACIA CONCEPTIONIS (Cuvier and Valencienne»). 



CABIKSA. 



Pristipoma oonceptionis Cuviee and Valenciennes, Hist. Nat. Poiss., vol. 



5, 1830, p. 200 (268) ; Conception de Chile. 

 Isacia conceptionis Jordan and Feslee, Rep. U. S. Fish Comm., 1888-91, 



p. 501 (1893). — Abbott, Marine Fishes of Peru, Proc. Acad. Nat. Sci. 



Phila., 1899, p. 350. — Steindachner, Herpet.-ichthyol., Ergebnisse einer 



Reise nach Siidamerika, Denlischr. Akad. Wiss. Wien, vol. 72, 1902, 



p. 28. — Stauks, Fishes from Ecuador and Peru, Proc. U. S. Nat. Mus., 



vol. 30, 1906, p. 789, fig. 9. 

 Isacia venusta Starks, Fishes from Ecuador and Peru, Proc. U. S. Nat. 



Mus., vol. 30, 1906, p. 789, fig. 10 ; Callao, Peru. 



One specimen, field No. 09625, 25.5 cm. long, from east side Santa 

 Rosa Island, Independencia Bay ; one specimen, field No. 503, 29.5 cm. 

 long, from Mollendo ; two specimens, field Nos. 09419-20, each 24 cm. 

 long, from Guanape North Island ; one specimen, field No. 479, 24 cm. 

 long, from Chincha North Island, region of Pisco, taken abundantly 

 in trammel net; four specimens, field Nos. 09134, 09139-41, respec- 

 tively 17.7, 16.2, 17, and 15.8 cm. long, from Lina Market, Callao; 

 twelve specimens, field No. 09455, 5.8 to 6.3 cm. long ; and two speci- 

 mens, field No. 09448 (part) each 4 cm. long, from Lobos de Afuera. 



A study of these sjDecimens and comparison of them with one of 

 the cotypes of /. vejiusta Starks, seem to indicate that the two species, 

 /. conceptionis and / venusta, are one. The larger specimens have 

 the smaller eye and the length of the head and depth nearly equal, 

 the head a little the longer of the two; the lower jaw projects more 

 strongly in some specimens than in others and more strongly in the 

 young than in the adult. The relative straightness of the vertical 

 border of the preopercle is variable, in some it is practically straight, 

 in others it is concave, Avith a long even curve; in still others it is 

 notched near the base. 



The table of comparative mefasurements on the following page will 

 indicate the variability of the species. 



Body compressed, dorsal and ventral outline equal and evenly 

 arched; head conical, snout pointed; jaws subequal in the adult, 

 usually the lower a little longer ; in the young the projection of the 

 lower jaw is more marked; mouth oblique; maxillary scarcely reach- 

 ing to the vertical from anterior border of eye ; teeth in broad villi- 

 form bands, narrowing posteriorly; teeth in the outer row slightly 

 enlarged ; vomer and palate without teeth ; vertical limb of the pre- 

 opercle variable from straight to concave or notched; margin den- 

 tate, the teeth at angle with wider interspaces; gillrakers long and 

 slender 8-1-20 to 23 ; the longest 1.75 in eye. 



Scales strongly ctenoid; portion of head in front of eyes naked; 

 soft dorsal naked or with few scales; both dorsals and anal fitting 

 into a groove; caudal scaled; anal with scales on membranes for a 

 short distance ; ventrals scaly ; pectoral w^ith a scaly area at base. 



Dorsals low, third dorsal spine longest, 2.65 in head, anterior rays 

 of soft dorsal longest; caudal forked; anal low, the spines rather 



