melanophores, all other chromatophores fade on 

 preservation in formaldehyde solution. 



Fin Development 



The dorsal, anal, caudal, and pectoral finfolds 

 are present in the youngest larva (3.6 mm). Dif- 

 ferentiation of the fin rays occurs in the following 

 sequence: 1) caudal, 2) first dorsal and anal, 3) 

 second dorsal and pectoral, 4) ventral. All fins are 

 essentially formed at 9 mm (Table 5). 



The pectoral fin rays ossify at 6 mm beginning 

 with the most dorsal rays, and the rest ossify ven- 

 trally. The full complement of 19 to 20 rays is 

 formed at 10 mm. 



The pelvic fin rays differentiate at 7 mm, and 

 the full complement of 5 rays is present at 9 mm. 



The dorsal and anal fin rays ossify anteropos- 

 teriorly. At 8 to 9 mm the full number of 8 spines in 

 the first dorsal fin and 1 spine and 35 to 40 soft rays 

 in the second dorsal is completed. The first dorsal 

 fin becomes arch-shaped as the spines increase in 

 height and remains continuous with the second 

 dorsal fin until in early juveniles (15-17 mm) a 

 deep notch demarcates the 2 fins. The anal fin rays 

 begin to ossify at 5 mm, and the full complement of 

 3 spines and 19 to 22 soft rays is completed at 10 

 mm. 



The caudal fin begins to develop at 4 to 5 mm in 

 a manner similar to that occurring in Elagatis 

 bipinnulata. The full complement of 9 dorsal and 

 8 ventral principal rays is present at 7 to 8 mm, 

 while the full complement of 10 to 11 dorsal and 

 of 9 to 10 ventral secondary rays is completed at 9 

 mm. 



FISHERY BULLETIN: VOL. 72, NO. 2 



Distribution and Spawning 



Juveniles of Seriola zonata (12-23 mm) have 

 been reported to be regular summer visitors in 

 Cape Cod waters which appear to be their most 

 northernly record (Mather, 1952). Adults have 

 been recorded from various points of the Atlantic 

 coast and in the Gulf of Mexico (Ginsburg, 1952). 



Larvae and early juveniles up to 26 mm were 

 taken in all months except in February, April, 

 September, and December. They were caught with 

 a 1-m plankton net in the Gulf Stream off Miami, 

 with dip nets at the pier of the Southeast Fisheries 

 Center in Biscayne Bay, and with neuston nets in 

 the Gulf of Mexico, Yucatan Channel, Straits of 

 Florida, and south Atlantic coast. The larvae oc- 

 curred in 1.4% of the net stations and constituted 

 1.8% of the larval carangids in the collection. The 

 occurrence of the larvae is too erratic to indicate 

 whether or not the spawning period is continuous 

 over 12 mo or broken into two parts, winter-spring 

 and fall. Spawning occurred mainly in offshore 

 waters in the eastern Gulf of Mexico, Yucatan 

 Channel, Santaren Channel, along the edge of the 

 continental shelf in the Straits of Florida, and in 

 the Carolina Bight off New Brunswick, Ga. (Fig- 

 ure 2). The planktonic larvae are presumably car- 

 ried along the Florida Current and Gulf Stream 

 and reach their northern limits as juveniles. 



Round scad, Decapterus punctatus 

 (Agassiz) 



Figure 4 

 Literature 



The early growth of this species were described 



Table 5. — Meristic characters of cleared and stained larvae and juveniles ofSeriola zonata. 



426 



