Systematic Position of the Euphausiacea

Abstract

ELSEWHERE in this issue of Nature (see p. 911) I have mentioned that, although the idea originated with Kemp, Gurney was the first to place the Euphausiacea in the order Decapoda, which he divided into two suborders, Euphausiacea and Eudecapoda. Gurney never intended to include the Euphausiacea in his Ray Society monograph, “Larvæ of Decapod Crustacea” (1942)—Euphausid literature is omitted from the earlier companion volume, “Bibliography of the Larvæ of Decapod Crustacea” (1939)—but a chance remark of mine prompted him to do so when his manuscript was almost, or quite, finished. This resulted in some inconsistency of treatment of the Euphausiacea, partly because he sometimes omitted to alter ‘Decapoda’ to ‘Eudecapoda’ where necessary, partly because he had already mentioned the Euphausiacea (as an independent order) here and there, in the same way as he mentions the Stomatopoda, for example. He did not explain why he altered the classification; Kemp's idea was quite new to him and he doubtless misunderstood what I said. That he had not considered the matter carefully is proved by the letter which he sent me in 1949 after we had again discussed the systematic position of the Euphausiacea (see p. 911 for his suggested solution, which has much in its favour). Incidentally, Nakazawa's claim, referred to by Gurney¹, that an economically important Japanese species of Sergestes has a free nauplius larva is sound. Recently I had the relevant passage translated; Nakazawa collected sixty eggs on August 6, from the fishing grounds, and from these he obtained the three naupliar Stages which he figured ; eighteen of the third-stage nauplii metamorphosed to the first-stage protozoea, which is an undoubted Sergestid larva.