EARLY DEVELOPMENT OF THE TEN-POUNDER 



625 



Tam.e 2. — Variation in number of body myomeres in in- 

 dividuals of different stages of development (specimens 

 grouped by size) 



preanal finfold extends from the anus anteriorly 

 to a point about one-third the distance to the head, 

 and lias a smooth and regular margin. By about 

 11 mm. (fig. 3) the dorsal portion of the finfold is 

 much reduced anteriorly, and its margin is more 

 uniform. The caudal portion is rounded, and the 

 margin invaginates dorsally and ventrally an- 



terior to the urostyle. By about 15 mm. (fig. 4) 

 dorsal ray bases are discernible, and by about 17 

 mm. (table 1) anal ray bases are present. Dorsal 

 rays are discernible at about 31 mm. (fig. 6), and 

 anal rays at 43.3 mm. (fig. 7), the largest lepto- 

 cephalus examined. 



The dorsal and anal finfolds diminish during the 

 leptocephalus period to the extent that the fins are 

 separated from it on the largest leptocephalus. 

 During the early metamorphic period (figs. 7 to 

 10) , the finfold is reduced to a small amount at the 

 caudal peduncle. The preanal finfold diminishes 

 more slowly, persisting through the mid-meta- 

 morphic period (figs. 11 and 12), and disappear- 

 ing early in the late metamorphic period (25- 

 30 mm.). 



At the end of the leptocephalus period (about 

 40-45 mm.) metamorphosis begins, and the larval 

 form starts to shrink in length. During the early 

 metamorphic period (down to a size of about 

 25 mm.), dorsal and anal rays remain fairly con- 

 stant in number, ranging 21 to 24 for the dorsal 

 and 12 to 15 for the anal (figs. 7 to 10) . The last 

 ray of both the dorsal and anal fin is branched at 

 its base at the size the leptocephalus begins to 

 shrink (40-45 mm. ) . During mid-metamorphosis 

 (25 mm. down to about 18-20 mm. and subsequent 

 length increase to about 25 mm.) dorsal rays range 



Figure 2.- 



-Leptocephalus, 5.3 mm. standard length, (a) Side view of one of fanglike teeth in upper jaw, showing end 



beveled on upper surface. 



