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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



presented descriptions or illustrations of individ- 

 ual specimens or a series: Meek and Hildebrand 

 (1923),Delsman (1926), Hildebrand (1934,1943), 

 Hollister (1936), Whitley (1937), Gopinath 

 (1946), and Fitch (1950). 



Van Kampen (1908) first identified and de- 

 scribed the larvae of the East Indian tarpon, 

 Megalops cyprinoides (Broussonet) (translated 

 from the German by Beebe, 1927) . Other contrib- 

 utors were; Delsman (1926), Hoist voogd (1936), 

 Hollister (1939), Gopinath (1946), Chidambaram 

 and Menon (1948), Alikunhi and Kao (1951), and 

 the Indian Council of Agricultural Research 

 (1951). Our knowledge of the larval develop- 

 ment of the Atlantic tarpon, T. atlanticus, is 

 meager: Hildebrand (1934 and 1943), Hollister 

 (1939), and more recently, the University of 

 Miami Marine Laboratory (anon. 1955). 



Jordan and Evermann (1896) recognized the 

 ribbonlike form of E. saurus larvae, and Smith 

 (1907) mentioned it, but larvae of this genus were 

 not described until 1923, when Meek and Hilde- 

 brand described leptocephali of E. affinis Regan. 

 Delsman (1926) illustrated a leptocephalus of 

 E. hcewaiensis Regan; Fowler (1931) illustrated 

 an E. saurus larva; Holstvoogd (1936) discussed 

 larval development of E. hawaiensis (in particu- 

 lar, the development of the kidney) ; Hildebrand 

 (1943) treated E. saurus; Gopinath (1946) added 

 notes on E. indicts (Swainson) ; 2 Alikunhi and 

 Rao (1951) illustrated and described in detail the 

 shrinking and metamorphosis of leptocephali of 

 E. saurus from laboratory reared specimens in 

 India; the Indian Council of Agricultural Re- 

 search (1951) discussed larval development of 

 E. indicus; 2 and Nair (1952) illustrated an 

 E. saurus leptocephalus. 



All these publications treat the shrinking and 

 metamorphosing larvae, but contain only specu- 

 lation on initial development of the leptocephalus. 



Regan's 1909 revision of the fishes of the genus 

 Elops is generally accepted today. Of the seven 

 species he lists, E. saurus, E. affinis, E. senegalensis 

 Regan, E. hawaiensis, E. australis Regan, E. mach- 

 nata Forsk., and E. lacerta Valenciennes 3 — 

 only E. saurus occurs on the Atlantic, coast of the 

 United States. Hildebrand (1939) found no evi- 



*E. indicus Swainson a synonym of E. saurus Linnaeus, after 

 Misra (1947). 



3 In accordance with Bailey (1951), single authority is used. 



denee of E. saurus moving through the Panama 

 Canal into the Pacific, or the Pacific coast species, 

 E. affinis, moving through the Canal into the At- 

 lantic. According to Regan (1909), the east and 

 west coast species are quickly separated on number 

 of gill rakers: E. saurus has 12-15 on the lower 

 limb, and E. affi.nis has 18-20. E. senegalensis, 

 found off West Africa, has 12-14 gill rakers, which 

 overlaps the 12-15 count for E. saurus; but E. 

 saurus has 103-118 scales in the lateral line, while 

 E. senegalensis has 94-98. Hildebrand (1943) 

 gives the following counts for several specimens 

 he examined : E. saurus, 10-15 gill rakers on lower 

 limb, 103-120 scales; E. ajfinis, 16-20 gill rakers, 

 104-116 scales; and E. senegalensis, 11-12 gill rak- 

 ers, 93-100 scales. 



Leptocephalid forms of Elops are readily sepa- 

 rated from those of Albula and Tarpon on one or 

 more characters, depending on the stage of de- 

 velopment. Prior to formation of fin rays, the 

 number of body myomeres can be used : Elops has 

 about 72-82 myomeres (generally more than 75), 

 Albula has about 66-72, and Tarpon has fewer. 

 One specimen examined by Hildebrand (1934) 

 had 52, and a 17.5-mm. specimen from T. N. Gill 

 collections had 57. Myomeres are discernible in 

 E. saurus larvae through the early and mid-meta- 

 morphic periods. Hildebrand (1943) stated that 

 after dorsal and anal fins become sufficiently de- 

 veloped to permit enumeration of the rays, the 

 species are readily separated by ray counts; E. 

 saurus has 21-25 dorsal rays and 14—17 anal rays, 

 whereas A. vulpes has 14-17 dorsal rays and 8-9 

 anal rays. His Tarpon larva of 20 mm. had 12 

 dorsal and 20 anal rays (the Gill specimen had 11 

 dorsal ray bases and 20 anal bases) . Albula lepto- 

 cephali may reach 3 or Sy 2 inches (about 76-88 

 mm.) before starting to shrink (Gill 1904) ; Elops 

 leptocephali begin shrinking at about 40 mm. The 

 size of Tarpon leptocephali before shrinking com- 

 mences is not known. 



I gratefully acknowledge the assistance given 

 by various staff members of the South Atlantic 

 Fishery Investigations during this study and in 

 the preparation of the manuscript. Special thanks 

 are extended to Frederick H. Berry and Hugh M. 

 Fields for their critical reading of the manuscript. 

 Special thanks are also due to Dr. Elbert H. Ahl- 

 strom for critical reading of the manuscript and 

 suggestions for presentation of data, and to Bruce 



