RICHARDSON ET AL.: EGGS AND LARVAE OF BUTTER SOLE 



two rows. The right dentary contains about 20 

 teeth (11 large conical teeth in the outer row and 9 

 smaller teeth in the inner row). The right pre- 

 maxillary contains nine larger teeth and six small- 

 er teeth. Teeth continue to increase in number 

 after transformation. A 44 mm juvenile possessed 

 about 40 teeth each on the left premaxillary and 

 left dentary and 14 teeth on the right dentary and 

 10 teeth on the right premaxillary. 



Neural spines ossify during notochord flexion 

 (Table 4; Figure 6). The first neural spine to ossify 

 lies just above the first haemal spine in the an- 

 terior abdominal region, and ossification proceeds 

 posteriorly and anteriorly. The last two neural 

 spines to ossify are those on the antepenultimate 

 and penultimate vertebrae. Ossification is usually 

 completed at about 16.5 mm. Haemal spines ossify 

 from anterior to posterior beginning with the first 

 haemal spine. The last two haemal spines to ossify 

 are also on the antepenultimate and penultimate 

 vertebrae. 



CHARACTERS 



10 12 14 16 



Standarcj length {in mm) 



20 



22 



24 



Figure 6. — Diagrammatic summary of the sequence of os- 

 sification of principal meristic structures in Isopsetta 

 isolepis. Dashed vertical lines indicate size range in which 

 notochord flexion occurs; open bars indicate meristic structure 

 is undergoing ossification; solid bars indicate meristic structure 

 is completely ossified. 



411 



