102 



U. S. p. R. R KXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



List of specimens. 



Family ATHERINIDAE, Bonap. 



The upper arcade of the mouth is formed by the premaxillaries, and the maxillaries, which 

 are situated behind, are tapering towards its free or posterior extremity, instead of being 

 dilated, as in all the other families, that of Mugilidae excepted. The upper jaw is very pro- 

 tractile, and the premaxillary and maxillary teeth and others, whenever extant, are generally 

 so small as to require to be magnified, in order to become visible. The branchiostegal rays are 

 six on either side. There are four gills on either side, but no pseudo-branchiae. The branchial 

 apertures are continuous under the throat. 



The body is covered with cycloid scales, and provided laterally with a silvery band, whilst 

 the line of mucous pores is wanting. There are two dorsal fins, widely separated, the 

 ventrals being abdominal. The stomach is a simple membranous pouch, without cul-de-sac; the 

 pyloric appendages are likewise wanting. The swimmimg bladder, however, is extant. 



S\ti.—Jilherinidae, Eonap. Syn. Vert. Syst. 1837.— Grd. in Gilliss' U. S. N. Astron. Exped. to S. Hemisph. II, 1855, 237. 



The large species of this family are much esteemed as an article of food by all the sea coast 

 people. . The small ones are equally delicate, although not made an article of commerce, for the 

 very simple reason that it is not remunerative. 



ATHERINOPSIS, G i r a r d . 



Gen. Char. — Palate toothless. Gape of the mouth directed obliquely upwards ; jaws even at their extremities ; snout 

 rounded or obtuse. 



Stm.— .^/fteriiiopsij, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 134 &, in GiHiss' U. S. N. Astr. Exp. to South. 

 Hemisph. II, 1855, 237. 



This genus has all the characters of Atherina, except that the palate is toothless. The 

 structure of the mouth is after the fashion of Mugil: the premaxillaries (intermaxillaries) 

 constituting its upper arcade at the exclusion of the maxillaries, which are situated behind the 

 latter. The lower jaw is even with the upper ; the gape of the mouth is directed more or less 

 obliquely upwards. The latter feature will at once distinguish the present genus from that 

 of Basiliclithys, in which the upper jaw projects beyond the lower. 



