630 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



scale. Holbrook (1860) gave 28 as the caudal ray 

 complement, which obviously does not include all 

 secondary rays. 



TEETH 



The 5.3-mm. leptocephalus (fig. 2) has four 

 teeth in a single row on each side in each jaw. 

 The anterior two in the upper jaw are the largest, 

 and are fanglike, uniform in diameter throughout 

 their length, and beveled at their tips. The two 

 remaining teeth in the upper jaw and those in the 

 lower jaw are gently tapered, with sharp tips. By 

 about 10 mm. there are 6 teeth in each side of each 

 jaw, the anterior 4 in each jaw larger than the 

 others. The number increases as the leptocephalus 

 grows, and at the size the larva begins to shrink 

 (about 40^5 mm.) there are about 10-11 teeth in 

 the upper jaw and 12-14 in the lower (the fang- 

 like teeth are difficult to distinguish from the 

 others at about this size) . During the early meta- 

 morphic period the number increases. During the 

 mid-metamorphic period it becomes difficult to 

 make an accurate count because of the varying 

 number of developing and partially exposed teeth. 

 At the end of the mid-metamorphic period the 

 maxillary teeth are in bands on the ventrolateral, 

 ventral, and ventromedial surfaces, irregularly set 

 vomerine teeth are present, and there are 3 pala- 

 tine teeth in a row on each side of the mouth. By 

 about 35 mm. (fig. 14) teeth are present on the 

 tongue. Juvenile and adult fish have pterygoid 

 teeth as well, and teeth are numerous in the jaws 

 and in the mouth. 



KIDNEY 



On an 11.2-mm. leptocephalus (fig. 3) two large 

 blood vessels extend from the digestive tract into 

 the body at the 51st and 52d myomeres. By about 

 20 mm. (fig. 5) it is evident that the blood vessels 

 enter a mass of tissue along the dorsal wall of the 

 digestive tract. Delsman (1926) showed this 

 tissue in his illustration of a 37-mm. E. hawaiensis, 

 but did not identify it. Holstvoogd (1936) dis- 

 cussed the development of the kidney in larval E. 

 hawaiemis, defining this tissue as mesonephros 

 and the two large blood vessels as branches of the 

 third mesenteric artery. During the early meta- 

 morphic period the kidney enlarges, and extends 

 from about the 48th to the 54th myomeres by the 

 end of the mid-metamorphic period (figs. 7 to 12). 



The body becomes opaque at about this stage, and 

 no further observations were made on the kidney. 



AIR BLADDER 



The rudimentary air bladder is visible as a slight 

 bulge in the dorsal wall of the digestive tract at 

 about the 35-36th myomeres on an 11.2-mm. lepto- 

 cephalus (fig. 3). On the largest leptocephalus 

 (43.3 mm.) it is a long, cylindrical, blind sac aris- 

 ing from the digestive tract at the 34th myomere, 

 directed dorsally into the body. During the early 

 metamorphic period it expands and lengthens, and 

 by about 30 mm. it extends to the vertebral column, 

 with its dorsal surface flattened against the col- 

 umn (fig. 9). During the mid-metamorphic 

 period the air bladder becomes broader and longer, 

 and on a 25.9-mm. late metamorphic larva it is 

 elongate and occupies a considerable portion of the 

 body cavity (fig. 13). By about 35 mm. in the 

 late metamorphic period (fig. 14) it is long and 

 thin, as in the juvenile and adult. 



GILL RAKERS 



Gill rakers are first visible on mid-metamorphic 

 larvae, 20-25 mm. Tables 8 and 9 give the num- 

 ber of gill rakers on the first arch of mid- and late 

 metamorphic larvae, juveniles, and adult. The 

 counts include rudiments. The ranges for speci- 

 mens exceeding 30 mm. are 5-7 for the upper limb 

 and 11-15 for the lower. For juveniles exceeding 

 70 mm. and adults the ranges are 5-7 for the upper 

 limb and 12-15 for the lower. Hildebrand (1943) 

 gave 5-8 for the uper limb and 10-15 for the lower ; 

 Regan (1909) gave 12-15 for the lower limb; and 

 Meek and Hildebrand (1923) gave 11-14 for the 

 lower limb. 



PSEUDOBRANCHIA 



Large pseudobranchia are present on mid-meta- 

 morphic larvae. 



BRANCHIOSTEGALS 



Branchiostegals were first visible on mid-meta- 

 morphic larvae, 5 on each side in a 21.5-mm. speci- 

 men (fig. 11). During the late metamorphic pe- 

 riod the number increases, and by about 35 mm. 

 there are approximately 30 on each side, with 

 usually more on the left side than on the right. 

 Holbrook (1860) stated that there is always one 

 more branchiostegal on the left side than on the 



