NATURAL SCIENCES OF PHILADELPHIA. 329 



Description of the Genus STEBEOLEPIS Ayres. 



BY THEODORE GILL. 



Genus STEREOLEPIS Ayres. 



Synonymy. 



= Stereolepis Ayres, Proc. California Acad, of Nat. Sci., vol. ii. p. 28, 1858. 

 Centropristis sp. Owen. 

 Oligorus sp. Gunther. 



Body oblong, highest at or behind the ventral fins, thence above rapidly 

 declining to the caudal fin with the vent posterior and the caudal pe- 

 duncle narrowed to the base of the fin. 



Scales rather small, mostly in very oblique rows, obliquely quadrangular 

 and as high as or higher than long, with the nucleus more or less behind 

 the centre, with concentric striae and folds, and radiating linear grooves 

 diverging from the nucleus towards the middle third of the anterior margin ; 

 the posterior margin unarmed and bordered by a membranous extension. 



Lateral line scarcely impressed, parallel with the back. 



Head nearly or quite as high as long, with the profile nearly straight and 

 rapidly declining from the nape to the snout; the forehead broad and 

 transversely convex. Scales on cheeks and opercula similar to those of the 

 body ; on the crown and middle of forehead between the eyes small and 

 imbedded in the skin. Snout, preorbitals and jaws naked. Eyes entirely in 

 the anterior half of the head, small and subcircular. Nostrils double, simple 

 nearly central between the snout and eye, and closely approximated. 

 Preoperculum rectangular, produced backwards towards its angle, which is 

 itself subangulated, slightly crenulated below its angle, entire above. Operculum 

 unarmed, neither spinous nor with a developed internal ridge. Suboperculum 

 behind the operculum below the angle of the latter, rounded behind and 

 above. 



Mouth rather large, with the cleft oblique, the supramaxillary con- 

 tinued to or below the eye. Jaws nearly even in front, lower shortest; 

 intermaxillaries nearly as long as supramaxillary, attenuated backwards ; 

 the supramaxillary widened backwards, obliquely truncated at the end and 

 with a supplementary piece above near the end. 



Teeth on the jaws densely villiform, in abroad band interrupted at the 

 symphysis and attenuated backwards. Vomer and palatine bones with 

 villiform teeth. 



Branchiostegal rays seven. 



Dorsal fin nearly double ; the spinous portion longer than the soft and 

 longer than the head, with nine spines, very low, convex above, the third 

 spine being longest ; the posterior porton with two spines and the soft part 

 nearly oblong, angulated before and behind, highest in front. Anal fin 

 similar to the second dorsal, but inserted further behind, its anterior portion 

 being under the posterior part of the latter. 



Caudal fin wide, subtruncated or emarginated behind. 



Pectoral fins angulated at its upper angle and with the posterior margin 

 obliquely convex. 



Ventral fins inserted below or behind the pectoral fins, of moderate size, 

 with the first ray longest. 



Type Stereolepis gigas, Ayres. 



Slereolepis is most closely related to the genus Oligorus of Gunther, and. 

 indeed the differences between the, two are not obvious from the data at 

 hand. It is quite possible that the Oligorus gigas, at least, belongs to 

 Slereolepis. The type of Stereolepis gigis Ayres is in the museum of the 

 Academy of Natural Sciences of Philadelphia, to which it was presented by 

 Mr. Geo. Davidson. Its weight was originally 360 pounds. 



1863.] 24 



