FISHES EMBIOTOCOIDAE AMPHISTICHUS AEGENTEU8. 



201 



List of specimens. 



AMPHISTICHUS, Agass. 



GEN. CHAR. Head rather large . Mouth largo ; jaws equal. Lips thin, lower one attached by a frenum to the symphysis 

 of lower jaw. Premaxillaries slightly protractile. Teeth stoutish, recurved, conical, and disposed upon a double row on both 

 jaws. Spinous portion of dorsal fin generally lower than the soft and sometimes equal to it in height. Anterior articulated rays 

 of anal divided like the rest and preceded by three spines, the second and third of which being nearly as deep as the first articu 

 lated ray. Scales of moderate development. Lateral line concurrent with the dorsal outline. One row of scales along the base 

 of anal. The dorsal groove extends from middle of spinous portion of dorsal fin to about the middle of soft portion of same fin. 

 Sheath formed by two rows of scales anteriorly, tapering into one posteriorly. 



SYN. Amphistichus, AGASS. in Amer. Journ. of Sc. 2d series, XVII, 1854, 367. GRD. in Proc. Acad. Nat. Sc. Philad. 

 VII, 1855, 323. 



This genus differs from Ennichihys, to which it bears a close affinity, by the conformation of 

 the lower lip, which is united by a frenum to the symphysis of the jaw instead of being free all 

 around. The spinous portion of the dorsal fin is also generally lower, and the dorsal groove 

 and sheath both longer. 



A young specimen of this genus we have caused to be represented on Plate XXVI, fig. 13, with 

 a view to illustrate some points in the morphology of the family as well as of the genus. Not 

 being able to refer it with certainty to any of the species of the same genus known to us, we 

 have preferred mentioning it without specific appellation. 



1. AMPHISTICHUS ABGKENTEUS, Agass. 

 PLATE XXXIX. 



SPEC. CHAE. General form sub-elliptical, more convex above than below. Snout anteriorly rounded. Posterior extremity 

 of maxillary reaching a vertical line passing behind the pupil. Anterior anal spines rather large. Sixty-eight scales in lateral 

 line. Branchiostegals, six. Bluish grey above, sides silvery with indistinct olivaceous transverse bands. Vertical fins and 

 ventrals olivaceous ; pectorals yellowish. 



SYN. Amphistichus argenteus, AGASS. in Amer. Journ. of Sc. 2d series, XVII, 1854, 367. GRD. in Proc. Acad. Nat. 

 Sc. Philad. VII, 1854, 141, 153 ; and, VII, 1855, 323. 



The specimen before us is rather more than eleven inches in total length, in which the head 

 enters about four times. The upper outline is very much convex, the frontal region steep, 

 sloping down towards the snout, with but a slight depression above the orbit. The body, as 

 usual, is very much compressed, its greatest depth being equal to two-fifths of the entire length. 



The mouth is rather large, the posterior extremity of the maxillary being even with a vertical 



line intersecting the posterior rim of the pupil. The front row of teeth are stoutish, conical, 



slightly curved, occupying the entire circumference of the mouth. The inner row is very 



exiguous. The lips are not fleshy, though well developed ; the lower one is attached to the 



2Ga 



