WATSON: DEVELOPMENT OF EGGS AND LARVAK OF WHITE CROAKER 



dorsal fin is continuous, with the first dorsal 

 much lower than the second initially. As growth 

 continues the anterior spines (except the first) 

 lengthen faster than the others, so that the dorsal 

 fin is deeply notched by the beginning of the 

 transitional period. 



Pelvic fin buds first appear between 5.3 and 

 5.9 mm and the first one or two elements become 

 visible at ca. 7.2 mm. Differentiation of rays pro- 

 ceeds toward the midline. The full complement 

 of one small spine and five rays usually is 

 attained by ca. 8.6 mm. 



Pectoral rays first develop at ca. 7.8 mm, be- 

 ginning from the upper pectoral base and pro- 

 ceeding downward. Five to nine upper rays are 

 present by ca. 8.6 mm and the full complement of 

 one small spine plus 17 to 18 rays is attained by 

 ca. 12.7 mm, just before the transition to the juve- 

 nile stage. The upper pectoral rays lengthen 

 much more than the lower rays as the fin grows, 

 changing its outline from rounded to bluntly 

 pointed. 



Head Spination 



Genyonemus lineatus acquires a number of 

 small spines on the head during larval develop- 

 ment. First among these is the spine at the angle 

 of the preopercle at ca. 3.5 mm. A second spine is 

 added just above the angle and a second row of 

 preopercular spines begins developing at ca. 4.5 

 mm. Preopercular spination subsequently in- 

 creases to between five and eight short spines in 

 each row by the end of the larval period. Early 

 juveniles may have as many as 12 spines in each 

 row. An interopercular spine develops at ca. 5.5 

 mm. Interopercular spines vary in number be- 

 tween one and four throughout larval develop- 

 ment. A subopercular spine develops at ca. 10.5 

 mm; as many as two or three may be present at 



the beginning of the juvenile stage. An opercular 

 spine first appears at ca. 10.5 mm and remains 

 throughout subsequent development. 



A minute supracleithral spine emerges at ca. 

 6.6 mm. Up to three additional supracleithral 

 spines may develop during the transition to juve- 

 nile. 



The first supraocular spine becomes apparent 

 at ca. 7.2 mm and is joined by an additional one or 

 two spines by ca. 9.2 mm. As many as eight small 

 supraocular spines may be present by the end of 

 the transitional period. 



Ossification 



Initial skeletal ossification in G. lineatus be- 

 gins with the cleithra. This is soon followed by 

 the jaws and associated bones, some of the 

 branchiostegals, opercular apparatus, and 

 branchial apparatus, and the posterior skull. 

 Premaxillary teeth appear next, followed by the 

 first pharyngeal teeth. Dentary teeth arise later, 

 about the beginning of vertebral and principal 

 caudal fin ray ossification. Initiation of dorsal 

 and anal soft fin ray and hypural ossification fol- 

 lows (Table 1). Anal fin spines precede the dorsal 

 fin spines, which are followed by pelvic and then 

 pectoral fin rays. All fin rays begin to ossify be- 

 fore their respective supporting structures. 

 Somewhat more detailed descriptions of ossifica- 

 tion follow. 



In the smallest larva cleared (2.6 mm) the only 

 stained structures are the cleithra and basioc- 

 cipital. By ca. 4 mm the posterior parasphenotic 

 has begun to ossify; parasphenotic ossification is 

 complete and the exoccipitals begin to ossify at 

 ca. 4.6 mm. Exoccipital ossification is essentially 

 complete and posttemporal ossification is begin- 

 ning at ca. 5.1 mm. Ossification of the frontal 

 bones initiates at ca. 5.6 mm. The lacrimal ap- 



Table 1.— Meristics of cleared and stained Genyonemus lineatus larvae. Larvae smaller than 4.64 mm are not included since fin 

 rays and vertebrae are not ossified below this size. Specimens between dashed lines are undergoing notochord flexion. 



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