Fishes of the Western North Atlantic 23 



348, pi. 18, fig. I (descr., ill., size, Maldive Is., see footnote 39, p. 19) ; Punnett, in Gardiner, as above, 

 1903: 362 (number of mj'otomes, sizes) ; Tattersall, in Herdman, Rep. Govt. Ceylon Pearl Oyster Fish., 

 Gulf of Manaar, suppl. 6, 1903: 222 (listed for Maldives and Zanzibar); Gibson, Trans. Linn. Soc. 

 Lond., Zool., (2) 13, igio: 24.1 (Maldives, by ref. to Forster-Cooper, 1903, Amfhioxides felagicus 

 perhaps its neotenic larva); Raff, Zool. Res. "Endeavour," Austral. Dep. Trade. Customs, I (3), 1912: 

 305 (listed for Louisiade Archipel., Maldives, Zanzibar, Torres Strait) ; Franz, Jena Z. Naturw., 5.?, 

 1922: 426, 427, fig. 30 (ill., myotome counts, size, Philippine specimens). 



Asymmetron orientale Parker, Bull. Mus. comp. Zool. Harv., 46, 1904: 46, pi. I, fig. 4 (descr., ill., Maldive 

 Is.) ; Hubbs, Occ. Pap. Mus. Zool. Univ. Mich., 105, 1922: 16 (ref.). 



Epgonichtkys caudatus Jordan and Evermann, Bull. U.S. Bur. Fish., 25, 1906: 191 (name only, Louisiade 

 Archipel.) ; Fowler, Mem. Bishop Mus., 10, 1928: 17 (name only, Louisiade Archipel.). 



Probable References:*" 



H eterofleuron {Asymmetron) lucayanum Haswcll, Rec. Aust. Mus., 7, 1908: 35 (Murray I., Torres Str., 



specimen subsequently named Notasymmetron by Whitley, 1932). 

 Notasymmetran caudatum Whitley, Aust. Zool., 7, 1932: 260, pi. 13, fig. 6 (descr., ill., Torres Str. spec); 



Fish. Aust., /, 1940: 250, fig. 290 (N. Queensland, Murray I., Torres Str.). 



Amfhioxides Larvae 



Synon}-ms: 



Branchiostoma (in part) Gunther, "Challenger" Rep., Zool., j/ (2), 1889: 43, for B. felagicum Gunther; 



not Branchiostoma Costa, I 834. 

 Am.'phioxides Gill, Amer. Nat., 2g, 1895: 458; type species, Branchiostoma felagicum Gunther, 1889. 

 "Pelagic larvae," Forster-Cooper, in Gardiner, Fauna Flora, Maldive Laccadive Archip., 1 (4), 1903: 354, 



pi. 6, fig. 3-6. 

 Asymmetron (in part) Pietschmann, in Kukenthal and Krumbach, Handb. Zool., 6 (i). Lief i, 1929: 110, 



fig. 107, for BranchiostoTna felagicum. Gunther, 1889. 



Grouf Characters. Small Lancelets, living pelagically, in which (as in larval Lance- 

 lets in general) the mouth is on the left side, without oral tentacles, the metapleural folds 

 are separate, one from another, so that there is no closed atrial cavity, and in which the gill 

 clefts are in a single row on the ventral side, but which grow to a greater length (up to 2 1 

 mm.)*' and develop a greater number of gill clefts than is usual for Lancelet larvae before 

 metamorphosis and which may show at least the rudiments of gonads. 



As pointed out above (p. 7), these Amphioxides are juvenile specimens that re- 

 tain their larval characteristics not only to a greater size than is characteristic of their 

 parent species*" but to a more advanced stage in their own development j they are not a 

 primitive group as was originally supposed.*' While they may develop gonads, as just 

 stated, there is no evidence that Lancelets ever become mature sexually as Amphioxides. 



44a. See footnote 35, p. 18. 



45. Forster-Cooper (in Gardiner, Fauna Geogr., Maldive Laccadive Archip., i, 1903: 352, pi. 4) reports as 

 Branchiostoma felagicum a 21 -mm. specimen from the central Indian Ocean that appears to be an Amfhioxides 

 because no trace of oral tentacles was to be seen. 



46. Larvae of this sort are known, technically, as "neotenic." 



47. Their larval nature, first suggested by Goldschmidt (Zool. Anz., 50, 1906: 443) and accepted by Gibson (Trans. 

 Linn. Soc. Lond., Zool., [2] 13, 1910: 239), was substantiated by Goldschmidt (Dtsch. Sud-polar Exped., //, 

 Zool. 3, 1909: 237), who discovered Amfhioxides in which the secondary series of gill openings had begun to 

 form, i.e., which had commenced their metamorphosis. 



