520 



ONTOGENY AND SYSTEMATICS OF FISHES -AHLSTROM SYMPOSIUM 



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Fig. 274. (A) Early postflexion larva (5.2 mm) of Selene sp. and (B) late postflexion larva (9.2 mm) of Hemicaran.x ainhlyrhynchus. 



Scale development proceeds dorsally, ventrally, and anteriorly 

 from this location. Berry (1960) presented a detailed account of 

 scute development and methodology for making counts. 



Oi^eo/o^. — Developmental osteology has been described for 

 Trachurns symmetricus (Ahlstrom and Ball, 1954); Decapterus 

 punctatus. Elagatis bipinnulata. Selene vomer, and Seriola :on- 

 a/a (Aprieto, 1974); and .4/M/r ^wa/<' (Miller and Sumida, 1974). 

 The sequence of ossification is the same for all of these species. 

 The cleithrum, premaxilla. and posterior preopercular angle spine 

 are first to ossify in preflexion larvae. Although the cleithrum 

 begins to ossify early, the pectoral and pelvic girdles do not 

 completely ossify until late in the transformation stage. Near 

 the beginning of notochord flexion, the maxilla, dentary, para- 

 sphenoid, supraoccipital, articular, frontal, angular, and bran- 



chial arches begin to ossify. However, much of the cranium does 

 not completely ossify until late transformation stage. Teeth form 

 along the anterior margin of the premaxilla as soon as it ossifies. 

 Aprieto (1974) noted that early ossification of bones related to 

 feeding is consistent with need for food following yolk resorp- 

 tion. The first branchial arch begins to ossify first with ossifi- 

 cation proceeding from the angle of the arch outward. The other 

 arches ossify similarly in sequence. Gill rakers develop following 

 ossification of the element on which they are attached. The full 

 complement of gill rakers is not attained until late transfor- 

 mation or early juvenile stage. Patches of small teeth form on 

 the upper pharyngeals of the third and fourth gill arches, and 

 the fifth arch has tooth patches along most of its length. Pha- 

 ryngeal teeth ossify early in the postflexion stage. 



Vertebrae begin to ossify next, in the middle of the flexion 



