FISHERY BULLETIN; VOL. 78. NO. 4 



7.3 mm 



7.6 mm 



Figure 4. — Postflexion and transforming larvae (7.1 and 7.6 mm) of Liopsetta putnami . 



stages, is snout to anus length/standard length. In 

 L. putnami it averages 43.6 and 41.2% for yolk-sac 

 and preflexion larvae while in P. americanus it 

 averages 33.3 and 37.6% for yolk-sac and preflex- 

 ion larvae. 



FIN DEVELOPMENT 



Newly hatched larvae of both L. putnami and P. 

 americanus have an undifferentiated fin fold ex- 

 tending along the body midline from the head 

 around the notochord tip to the anus. No other fins 

 were observed on the smallest L. putnami larva 

 (3.1 mm); however, the smallest P. americanus 

 larva (2.4 mm) and a 3.8 mm L. putnami larva had 

 undifferentiated pectoral fin folds. 



Pectoral fin rays are the first to begin develop- 

 ment in both L.pii^namt and P. americanus, by 5.2 



902 



and 5.3 mm. However, pectoral fin rays are the last 

 to complete development, completed between 8.5 

 and 13 mm in L. putnami (Laszlo 1972) and by 13 

 mm in P. americanus. Pectoral fin length is 

 greatest in both species during the preflexion and 

 flexion periods, averaging 7.8 and 7.1% SL in L. 

 putnami and 7.7 and 7.8% SL in P. americanus , and 

 shortest during yolk-sac and postflexion stages, 

 averaging 3.8 and 5.0% SL in L. putnami and 3.0 

 and 4.7% SL in P. americanus. Dorsal, anal, and 

 caudal fin rays begin development in preflexion L. 

 putnami and P. americanus at —5.9 and —5.6 mm. 

 Adult complements of dorsal and anal fin rays and 

 principal caudal fin rays are present by —8 and ~7 

 mm. Fin rays within dorsal and anal fins of both 

 species seem to form simultaneously except the 

 two or three posteriormost rays in each fin which 

 form last. Principal caudal fin rays form first and 



