FISHERY BULLETIN: VOL. 81, NO. 4 



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FlGl'RK 4. — Prolarval and early postlarval stages of the longhorn sculpin, Myoxocephalus octodecemspinosus, 

 artificially propagated in the laboratory: A) newly hatched prolarva6.8 mmTL, scale = 1 mm; B) postlarva7.7 mm 

 TL ( 10 d old), scale = 1 mm; C) postlarva8.7 mmTL (20 d old), scale = 1 mm; D) postlarva 8.8 mmTL (30 dold), 

 scale = 1 mm. Measurements refer to mean total length of larvae. 



head and the dorsal aspect of the gut region were so 

 dense as to produce an almost uniformly dark 

 appearance. About 25 spots were along the ventral 

 line of the tail, including some beyond the point of 

 flexion. There were four preopercular spines on each 

 side, and two pairs of head spines. The nostrils were 

 almost completely constricted (Fig. 5B). 



Longhorn sculpins metamorphosed from the larval 

 stage at 5 1-58 d, when they were about 12.0 mm TL. 

 A small remnant at the caudal peduncle and incom- 

 plete separation of the two dorsals were the only 

 relics of the embryonic finfold. There were nine 



spines in the first dorsal. This fin was shorter than the 

 second dorsal and approximately equal in height; fish 

 at this stage did not yet exhibit the higher first dorsal 

 characteristic of adults. Second dorsal fin had 14 or 

 1 5 rays. Anal fin had 1 4 rays. Pelvic fin had three rays. 

 Pectoral fins had 17 or 18 rays and extended beyond 

 the origin of the second dorsal. Five spines were now 

 on each cheek, and the uppermost had begun growing 

 strongly, signalling the development of the long 

 cheek spine characteristic of adults. Two pairs of 

 head spines were fusing and appeared as a single 

 large flesh-covered structure. There was one pair of 



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