Figure 2. — HemitHpterus americanus. Early postlarva, 17 February 1975: 15.5 mm TL. 



active by this time, but still spent most of the time 

 on the bottom. By 2 March, the larvae were no 

 longer attracted to light. 



Toward the end of March, the caudal fin had 8 or 

 9 ray rudiments. Rays began to develop in the 

 second then first dorsal fins followed by the pec- 

 toral fins. The caudal peduncle remained unpig- 

 mented. Spines began to form on the preopercu- 

 lum. Greyish-tan fleshy tabs developed dorsally 

 behind the head and around the occiput. 



By 20 April, the largest specimen (Figure 3) had 

 14 and 11 elements in the first and second dorsal 

 fins, respectively. The anal had 10 rays and the 

 caudal had 12, at about 20 mm TL. Both the 

 dentary and premaxilla had 15 teeth on each side. 

 The preopercular spines became more prominent. 

 The hypural plate began to form. The ratio of the 

 head length to total length was 3.6; of the pre- 

 dorsal length to total length, 3.8; and of the eye 

 diameter to head length, 2.7. The iris became less 

 silvery. Dense pigmentation developed on the in- 

 terradial membrane of the first dorsal fin between 

 elements 1 through 4 and 8 through 12. Similar 

 pigmentation developed in the second dorsal fin 

 (between elements 3 and 7) and the postanal fin 



fold (between elements 3 and 6). Few melano- 

 phores were scattered between these dense areas 

 of pigment. This larva utilized much of the water 

 column during active periods and spent little time 

 on the bottom. 



Acknowledgments 



I thank Neal R. Foster of the Academy of 

 Natural Sciences of Philadelphia for providing 

 laboratory facilities and for his advice on the care 

 of the larvae and the preparation of the manu- 

 script, and Joanne and Wayne Laroche of the 

 School of Oceanography, Oregon State University, 

 for supplying comparative material to aid in the 

 identification of the larvae. 



Literature Cited 



BEAN, T. H. 



1897. Notes upon New York fishes received at the New York 

 Aquarium, 1895—1897. Bull. Am. Mus. Nat. Hist. 

 9:327-375. 

 BIGELOW, H. B., AND W. C. SCHROEDER. 



1936. Supplemental notes on fishes of the Gulf of 

 Maine. Bull. U.S. Bur. Fish. 48:319-343. 



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FIGURE 3.— HemitHpterus americanus. Postlarva, 20 April 1975: ca. 20 mm TL (the pectoral fin has been deleted for the sake 



of clarity). 



469 



