264 NEW-YORK FAUNA. 



GENUS CHATCESSUS. Cuvier. 

 The last dorsal ray prolonged into a filament. Mouth edentate. 



THE SPOTTED THREAD HERRING. 



ChATCESSUS SIGNIFER. 

 PLATE XLI. FIG. 132.— (STATE COLLECTION.) 



Characteristics. Back with three or four dusky lines. A round black spot on the shoulder, 

 behind the branchial aperture. Anal distinct. Length 8-12 inches. 



Description. Body compressed, elliptical ; total length to the depth as one to three nearly. 

 Scales large, irregularly rounded, deeper than long, and covering the base of the anal rays. 

 Abdomen serrate, with thirteen distinct rhomboidal acute scales between the ventrals and the 

 vent, and eighteen smaller, scarcely prominent ones anterior to the ventral fins. Head small, 

 nearly one-fifth of die total length ; its summit plane. Eyes large, prominent, nearer the tip 

 of the snout than to the edge of the branchial aperture. Upper jaw broadly emarginate ; 

 lower jaw longest, with a broad expansion above, which is received within the upper jaw. 

 The point of union of the branchial rays prominent ; the posterior branchial ray much dilated. 

 Opercle large, rounded above ; margin vertical, rounded above, and with deep emargination 

 between its lower angle and the second posterior branchial ray. Tongue small, distinct, 

 smooth. 



The dorsal fin sub-triangular ; the first short, 0'2 long ; the second, third and fourth rays 

 successively higher and simple ; the fifth longest ; from this, the branched rays descend in a 

 broadly emarginate line to the last, which is prolonged into an articulated filament, equal in 

 length to the greatest depth of the body ; at the base of this ray, and beliind it, is a small 

 tubercle. Pectorals feeble, falciform, and of eighteen rays ; beneath it a rudimentary acces- 

 sory plate. Ventrals very short, near the edge of the abdomen, and with its base under the 

 twelfth dorsal ray ; these fins are also furnished with slight accessory plates. Anal very low, 

 but distinct ; the last ray simple, articulate, and longer than the preceding. Caudal deeply 

 forked ; the external entire ray filamentous. Branciiial rays seven. 



Color. Bluish above, with a series of dark points along the sides of the back, forming four 

 or five longitudinal lines. A round black spot behind the upper part of the branchial aperture. 

 Pectorals, ventrals and anal white. Dorsal and caudal yellow ; the membrane finely punc- 

 tate with black, and bordered with dusky. Irides white varied with yellowish. 



Length, 8'0. Greatest depth, 2"5. 



Fin rays, D. 19 ; P. 18 ; V. 8 ; A. 21 ; C. 19 f . 



The Thread Herring can scarcely be confounded with the C. thrissa of Bloch. It is more 

 closely allied to the Megalops oglina of Lesueur, but from this it is sufficiently distinct. It 



