442 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
early period the preopercular spines are absorbed into the substance of 
the preopercnlum and disappear. The spinous dorsal and the teeth are 
still retained. In this condition it remains for some time, ‘^he spinous 
dorsal, however, gradually losing its relative size, while the soft vertical 
fins increase. In this stage the species belongs to the genus Dolioclon 
of Girard. At a later period the membrane connecting the dorsal spines 
has become obsolete, and the species then represents the genus Tracliy- 
notus^ as understood by Cuvier and Valenciennes, and others. Finally, 
in old age, the teeth of the javns, palate, and ])haryngeal bones have fallen 
out, and the lobes of the dorsal, anal,, and caudal fins attaia^d their 
greatest extension and become pointed. This final stage has been made 
known by Holbrook under the new generic name of Bothrolccmus^^ (Clill, 
Proc. Acad. Kat. Sci. Phila. 1862, 410). The pseudobranchim also dis- 
aiipear in old specimens. The species of Trachynotus are among those 
most highly valued as food-fishes, {rpayoq, rough j back.) 
o. Body without dark bands. 
b. Vertical fins without black. 
696. T. caroMsuiis (L.) Gill. — Common Pompano. 
Uniform bluish above, sides silvery, golden in the adult, without 
bands; fins plain silvery or dusky. Body oblong ovate, elevated, pro- 
file forming a gentle curve from the middle of the back to the snout, 
where it descends abruptly. Dorsal and anal falcate, their lobes reach- 
ing when depressed nearly to the middle of the fin ; pectoral reaching to 
opposite the vent. Gill-rakers short, slender in the young, becoming 
thick in the adult. Head 4 ; depth 2^. D. VI-I, 25; A. H— I, 23. L. 
18 inches. West Indies, north to Cape Cod; the most valued food-fish 
of our southern waters. 
(Gastcrosfeus caroVuim Linn. Syst. Nat.: Trachynotus pampanus GUnther, ii, 484; 
Bothroloimifs pampanus Holbrook, Ichth. S. C. 1860, 81.) 
bh. Vertical tins largely black. 
691'. T. ovatus (L.) Gthr. 
Bluish, sides silvery; lobes of the dorsal and anal more or less black. 
Body comparatively deep. Head about 4. Depth If to 2. D. VI-I, 
19 ; A. II — I, 18. In all warm seas ; north to Virginia on our Atlantic 
coast. 
{Gasterosteus ovahis L. Syst. Nat.; Gunther, ii, 481.) 
69§. T. gorcensBS C. &. V. 
Dorsal, anal, and caudal lobes black. Snout obliquely truncated; 
maxillary reaching to below the centre of the eye; anterior rays of dor- 
