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Fishery Bulletin 89(2). 1991 



gill rakers on the lower arch of the 1st gill arch in tran- 

 sitional specimens, but none on the upper arch. Epi- 

 branchial gill rakers were present in all juveniles ex- 

 amined (Table 4). The adult complement of 23-26 was 

 present at about 50 mm. 



An uninterrupted row of medial gill rakers is present 

 on the 3d and 4th arches in 17-mm juveniles, but those 

 on the 1st and 2d arches appear at 30-35mm SL. There 

 are 2 pseudobranchiae in the larva and transitional 

 specimens. The number generally increased to 3 in 

 juveniles of about 15mm SL, and 6-7 in juveniles 

 >45mm SL. 



Dentition The single larval specimen is toothless, 

 but all transition specimens have teeth on the den- 

 tary, premaxillary, and basihyal, and, except for two 

 individuals, on vomer and palatines as well (Table 3). 

 Earliest appearances of maxillary, mid-dentary, and 

 basibranchial teeth were in 16-17 mm juveniles. As 

 in H. latifrons, there were more dentary than max- 

 illary teeth in early stages; however, the number of 

 maxillary teeth increased rapidly, becoming equal to 

 that of the dentary by about 25 mm SL and more 

 numerous after 35 mm (Table 4). Vomerine teeth 

 numbered 2-5 and palatines 1-3 in the 16-50 mm SL 

 range. In individuals 16 mm and larger, there were 

 3-12 teeth positioned around the perimeter of the 

 basihyal, and 2-14 on the basibranchial. After a gradual 

 increase, mid-dentary teeth numbered about 10 in 

 individuals >50mm SL. Mesopterygoid teeth appeared 

 after 65mm SL, and ectopterygoid teeth were found 

 only in large adults. 



Photophores The posterior gular organ (G0 2 ), sub- 

 opercular organ (SBO), intraventral organ (IVO), and 

 the orbital organ (OO) are the only photophores in in- 

 dividuals as large as 50mm; they are covered over or 

 lost in adults. The IVO photophore is located behind 

 the yolksac (Fig. 2A). It becomes enclosed in a sub- 

 conical, black pouch with a silvery, inner lining during 

 the transitional period. The wider end of the pouch 

 faces anteriorly and is covered by a transparent mem- 

 brane. The photophore is located at the narrower, 

 posterior end of the pouch, and is directed anteriorly. 

 The other photophores are similarly housed in anterior- 

 ly facing, subconical pouches with a wider anterior 

 opening and greater silvery surfaces. 



Adult photophores face ventrally. Most begin appear- 

 ing in juveniles. At 50-60 mm, the following organs 

 begin to form: the jugular organ (JO) located between 

 the bases of the pectoral fins; the thoracic organ (THO) 

 behind the JO; the midventral organ (MVO) behind the 

 THO and just before the pelvic fin bases; a pair of 

 supraventral organs (SVO) just dorsal to the base of 

 each pelvic fin; and the supra-anal organs (SAO) on 

 both sides of the anus. The JO photophore first appears 

 as one or more longitudinal bars (as in H. latifrons), 

 but at about 65 mm begins to transform into a short 

 transverse bar. Two more transverse bars, the THO 

 and MVO, form behind the JO on the widely flattened 

 ventral margin. Also appearing by 65 mm are several 

 branchiostegal organs (BRO) on the branchiostegal 

 rays, a postorbital organ (POO) just behind the eye, a 

 pair of postanal organs (PAO) at about the middle of 

 the anal fin, and an infracaudal organ (ICO) ventrally 

 on the caudal peduncle. The anterior gular organ 



