628 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 3. — Number of dorsal fin rays on individuals of different stages of development (specimens grouped by size) 



: Ray bases, no rays have formed. 



1 Ray bases, no rays have formed. 



period the. number increases, and by about 30-35 

 mm. in the late metamorphic period the number 

 is within the range for adults, 16-19 (figs. 11 to 

 14) . For specimens exceeding 80 mm. in standard 

 length, the range was 17-18. Holbrook (1860) 

 listed 18 pectoral rays. 



Pelvic fin. — The pelvic fin buds were first evi- 

 dent on a 34.0-mm. early metamorphic larva 

 (fig. 8) at about the 36th myomere and just pos- 

 terior to the air bladder. Kays develop during the 

 mid-metamorphic period. Five rays were visible 

 (after staining with alizarine red) on a 21.5-mm. 

 specimen (fig. 11). By about 35 mm. in the late 

 metamorphic period the full complement is pres- 

 ent, 14-15 (table 6). Holbrook (1860) listed 

 15 pelvic rays. 



Caudal fin. — At 5.3 mm. (fig. 2), the leptoceph- 

 alus has no caudal fin. The urostyle begins to 



tip up slightly by about 10 mm., and four hy- 

 purals are visible (fig. 3) . By about 15 mm. 8 or 9 

 hypurals and 19 caudal rays are discernible, and 

 the posterior margin of the fin is somewhat trun- 

 cate (fig. 4). By about 20 mm. the fin is forked, 

 and one secondary ray is present (fig. 5). The 

 largest leptocephalus (43.3 mm.) has 19 principal 

 and 1 dorsal secondary and 2 ventral secondary 

 rays, with 6 principal rays branched in each lobe 

 (fig. 7). During the early metamorphic period 

 (43.3 mm. down to about 25 mm.), the complement 

 remains constant at 1 + 19 + 2 (dorsal secondary, 

 principal, and ventral secondary rays) (figs. 7 to 

 10). Through the mid-metamorphic period (25 

 mm. down to about 18-20 mm. and up to about 25 

 mm.) the number of rays increases to 3 + 19 + 3, 

 and the complement of branched rays is complete 

 (9 in the dorsal lobe and 8 in the ventral lobe). 



