FAMILY CLUPIDA: — HYODON. 265 
appears in our waters about the beginning of September, where it is often called the Shad 
Herring. It has also the names of Thread Herring and Thread-fish, in allusion to its last 
filamentous dorsal ray. 
(EXTRA-LIMITAL.) 
C. oglina. (Lesunur, Ac. Sc. Vol. 1. p. 359.) Back almost straight; with three longitudinal black 
bands on each side. Anal fin hardly visible. Dorsal not emarginate. Length 8 inches. New- 
port Harbor. 
C. cepedianus. (In. p. 361.) Pectorals reaching beyond the base of the ventrals, which are placed 
anterior to the dorsal. Length eight to twelve inches. Delaware and Chesapeake. 
C. ellipticus. (Kirtianp, Zool. Ohio, p. 195.) Hickory or Gizzard Shad. Undescribed. Ohio 
River. 
GENUS HYODON. Lesueur. 
Form of the preceding. Scales large, deciduous. Abdomen thin, trenchant, but not serrated. 
Dorsal and anal nearly opposite. Branchial rays eight or nine. Teeth momute and 
curved, on the jaws, tongue, vomer and palatines. Eyes very large. 
THE RIVER MOON-EYE. 
Hyopon TERGISUS, 
PLATE XLI. FIG. 130.— (CABINET OF THE LYCEUM.) 
Hiodon tergisus. Lesurur, Journ, Acad. Nat. Sc. Vol. 1, p. 366. 
H. tergissus, Moon-eyed Herring. Kirtuanp, Zoology of Ohio, p. 170 and 195, 
Characteristics. Anal large and rounded anteriorly, with its posterior portion low. Lateral 
line nearly straight. Dorsal margin concave. Length 9 inches. 
Description. Body compressed; the dorsal outline very slightly arched from above the 
branchial aperture, thence descending to the tip of the snout, forming a slightly concave pro- 
file. Scales large, caducous, membranous on their free edges, and with three radiating ele- 
vated lines ; the radical portion striated in radiating lines, irregularly truncate on the margin. 
The scales ascend high up on the base of the caudal. Head small. Opercle with a slight 
notch near its upper margin, which is filled up with a membrane. Eyes very large, and 
nearly filling up the whole space between the angle of the jaws and the upper part of the 
head. Snout in front descending almost vertically. Nostrils double, contiguous, patent; 
both nearer the point of the jaw than to the eyes. Conic teeth in a single row above ; in 
several rows on the lower jaw. Tongue with several series of teeth, of which the outer on 
each side are largest. Teeth also on the vomer, and very minute ones on the palatines. 
The dorsal fin with the first three rays simple, the fourth and fifth longest, the twelfth 
shorter than the following ; this fin arises shortly anterior to the anal. Pectorals 1°3 long, 
Fauna — Parr 4. 34 
