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Fishery Bulletin 92|2). 1994 



spine was forming by 5.0 mm and 

 was difficult to locate on larvae 

 not cleared and stained. A spine 

 also was present along the poste- 

 rior margin of the interopercle 

 near its junction with the 

 subopercle by 6.0 mm (Fig. 2). The 

 interopercular spine often was 

 hidden by the large spine at the 

 preopercular angle but was more 

 easily located as the preopercular 

 angle spine regressed. 



Atlantic spadefish larvae have 

 numerous spines and ridges scat- 

 tered over the head. A thickened 

 ridge was visible dorsally along 

 the supraoccipital of 2.0-mm lar- 

 vae. This thickened ridge became 

 a small, peak-like, median supra- 

 occipital crest with a single, dor- 

 sally directed spine by 2.5 mm. 

 The supraoccipital spine began to 

 regress by 5.0 mm and was re- 

 sorbed by 10.0-10.5 mm. A su- 

 praorbital ridge was present by 

 3.5 mm. This ridge became ser- 

 rate by 4.0 mm. Small serrate 

 ridges were visible along the dor- 

 sal margin of both the lacrimal 

 and jugal bones (i.e. first and sec- 

 ond suborbitals; Gregory, 1933) 

 and third suborbital bone by 5.0 

 mm. Spines or spinous ridges 

 were also visible along the fourth 

 and fifth suborbitals, dermo- 

 sphenotic (i.e. sixth suborbital), 

 posttemporal, pterotic, tabular, 

 and supracleithral bones by 6.0 

 mm. The ventral margin of the 

 jugal bone near the posterior margin of the maxil- 

 lary had a single, ventrally directed spine by 7.0 mm 

 (Fig. 2). Individual spines were also scattered over 

 the frontal and occipital bones of young Atlantic 

 spadefish. The bases of these spines were covered 

 by integument so that only a portion of each spine 

 was visible (Fig. 3). All head spines and spinous 

 ridges were present in the largest specimen exam- 

 ined (12.5 mm) but were difficult to locate on lar- 

 vae not cleared and stained because of heavy body 

 pigment. 



Teeth in Atlantic spadefish were placed in an in- 

 ner and outer band. Teeth first appeared in a single 

 band on the premaxillary and anteriorly on the 

 dentary at about 2.5 mm. Teeth were pointed and 

 closely spaced. A second band of teeth formed along 



Figure 1 (Continued) 



the upper and lower jaws by 4.0 mm; the outer band 

 was slightly larger than the inner band. Teeth were 

 added along the upper and lower jaws as larvae de- 

 veloped (Figs. 1 and 2). 



Specialized spinous scales or "pre-scales" began to 

 develop at about 5.5 mm. Pre-scales were character- 

 ized by a single, elevated, posteriorly directed spine 

 that was positioned near the center of the scale. Pre- 

 scales developed first on the head and later ap- 

 peared anteriorly along the lateral midline. Pre- 

 scales were added outward toward the dorsal and 

 ventral midlines and proceeded in a posterior direc- 

 tion, covering the body by 10.0 mm. 



The first bones to ossify were the preopercular 

 spines, supraoccipital crest, premaxillary, dentary, 

 and cleithrum. Three predorsal bones (i.e. supra- 



