osteology of yellowfin menhaden larvae is treated 

 rather briefly in this paper. Ossification of most 

 structures occurred at a smaller size in yellowfin 

 menhaden than in either Atlantic thread herring 

 or scaled sardines, but the sequence of develop- 

 ment was similar in all of the species. 



No bones were ossified in our 5.2-mm specimen, 

 but the cleithra were lightly stained in 6.1- and 

 7.2-mm specimens. Cleithra were well stained in a 

 7.4-mm specimen, but no other bones were ossified. 

 Slight ossification of the maxillaries and den- 

 taries, in addition to the cleithra, was observed in 

 our 8.6-mm larva. At 10.5 mm, the caudal fin 

 complex began to ossify, cranial bones were lightly 

 stained, and 8 maxillary and 3 dentary teeth 

 were present. Vertebral centra were beginning 

 to stain at 12.3 mm; neural and hemal arches were 

 developing, but were unstained. Dorsal fin rays 

 were ossifying at 12.3 mm. Also, cranial bones 

 were ossifying, the hyoid apparatus was stained, 

 11 teeth were present on the maxillaries, and 4 

 were present on the dentaries. At 16.2 mm, most of 

 the major skeletal structures were at least partly 

 ossified. Rays in median and paired fins were 

 stained as were neural and hemal spines along the 

 vertebral column. Premaxillaries and posterior 

 supramaxillaries were ossified in this specimen. At 

 18.0 mm, the degree of stain uptake increased in 

 most bones. Also, ribs were stained, anterior 

 supramaxillaries were stained, and 16 maxillary 

 teeth were present, but the dentary bore no teeth. 

 Ossification was complete in our 25.3-mm 

 specimen. A total of 25 maxillary teeth but no 

 dentary teeth were present. Dentary teeth are a 

 transient larval character in B. smithi. One large, 

 erect tooth was present on the basihyal of our 

 18.0-mm specimen, and two were present on the 

 25.3-mm specimen. Basihyal teeth also were 

 reported from Atlantic thread herring and scaled 

 sardine larvae (Richards et al. 1974; Houde et al. 

 1974). 



The caudal fin complex of yellowfin menhaden 

 developed much like that of scaled sardine, and we 

 give a brief description here, using the ter- 

 minology of Houde et al. (1974) in their description 

 of scaled sardine. Some cartilaginous, principal 

 caudal rays developed in specimens as small as 7.5 

 mm. Flexure of the notochord and appearance of 

 cartilaginous hypural plate elements occurred at 

 about 8.5 to 9.0 mm. Our 10.5-mm specimen had 

 stain uptake in the proximal parts of the 19 prin- 

 cipal caudal rays, and the first uroneural was 

 slightly stained. Hypural elements were present 



but unstained. At 12.3 mm, the 19 principal caudal 

 rays were fully stained, the second ural vertebra 

 was stained as were the first and second 

 uroneurals, and the parhypural was lightly 

 stained. The hypurals were present but unstained 

 as were two epural bones. Ossification was 

 progressing in our 16.2-mm specimen. Both the 

 first and second ural vertebrae were stained, the 

 six hypurals were stained, the parhypural was well 

 stained, and all three uroneurals were now 

 stained. In addition to the 19 principal caudal rays, 

 8 dorsal procurrent caudal rays and 6 ventral 

 procurrent caudal rays were stained. Two epurals 

 were present on this specimen but were unstained. 

 At 18.0 mm, all of the bones in the caudal fin area 

 were at least partly ossified. The two epurals were 

 now slightly stained, and 9 dorsal plus 8 ventral 

 procurrent caudal rays were present and stained. 

 The 25.3-mm specimen had all caudal fin bones 

 ossified. The two epurals were well stained on this 

 specimen, these bones being the last to ossify in 

 the caudal fin complex. 



Pigmentation 



Melanophore distribution on yellowfin 

 menhaden larvae is similar to other clupeid larvae, 

 but there are some distinctive characteristics 

 which may serve to distinguish them from other 

 clupeid larvae with which they can occur. 

 Melanophores were contracted on some specimens 

 and expanded on others, accounting for some of 

 the apparent variability among individuals. Our 

 illustrated specimens (Figures 2-5) have pigment 

 that is typical of most specimens of those lengths. 



Head Region 



Newly hatched yellowfin menhaden larvae have 

 several tiny melanophores on the snout and a few 

 over the brain. Within 1 day after hatching those 

 melanophores have migrated or disappeared, 

 because no pigment is present on the heads until 

 larvae attain about 9.0 mm. The eyes became pig- 

 mented at about 4.5 mm, at 1 day after hatching. 

 Typical pigmentation on the pectoral symphysis 

 and over the heart developed at 4.5 to 6.0 mm. One 

 or two melanophores appeared on the pectoral 

 symphysis after yolk absorption when larvae were 

 4.5 to 5.0 mm. Those melanophores developed into 

 two distinct pairs by 7.0 mm. Either one or two 

 melanophores developed over the heart at about 

 6.0 mm. A single melanophore occurred at the 



668 



