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The Larvae of Certain British Crangonidae. 



By 

 Robert Gurney, B.A. (Oxon. 



In the present paper I propose to give a brief account of the larvse 

 of two species of Crangonidse — Cheraijhilus trisinnosus and ^geon 

 fasciatus. I shall not do more than describe the most characteristic 

 features of the larva, as I hope soon to publish a more complete 

 account of the development, with illustrations.* 



The larvffi of Decapod Crustacea are a conspicuous feature of the 

 plankton during the greater part of the year, and their identification 

 being usually impossible without their complete metamorphosis being 

 known, it seems to me to be worth while giving, not only a description 

 of the above-mentioned larvse, but also a diagnostic table for the 

 distinction of all those Crangonid larvse at present known. 



In drawing up the table given I have depended largely on the paper 

 of G. 0. Sars,f but I have been able to confirm his description of the 

 larvse of Crangon vulgaris, Cheraphihcs nanus, and Pontophilus spinosus. 



Of our commoner British species there remains only ^geon smiptus 

 to be investigated. I have found no larva in the tow-net collections 

 during the present year not referable to one or other of the species 

 named, and have only seen a single specimen of the adult. Its 

 larva must therefore remain for the present unknown. 



The Larva of Oheraphilus trispinosus (Hailstone). 



An abundant supply of zoseas was obtained by keeping berried 

 females in the laboratory tank till the hatching of the eggs. Un- 

 fortunately it was found impossible to keep the zoseas alive beyond the 

 first moult, and in spite of the commonness of the adult, very few 

 larvc"e have been found in the tow-nets. 



The first larva varies in length from TS to 2-0 mm., not including 



* [This account has now appeared. See R. Gurney, "Metamorphoses of the Decapod 

 Crustaceans JEgeoii {Crangmi) fasciatus (Risso) and ^geon (Crangon) trispinosis (Hail- 

 stone)," Proceed. Zool. Soc, London, 1903, vol. ii. p. 24. E. J. A.] 



t "Bidragtil Kundskaben om Decapodernes Forvaudlinger, III. fani. Crangonidse."' 

 Arch. f. Mathem. oy Naturvid., xiv. (1890). 



NEW SERIES. — VOL. VI. NO. 4. 2 R 



