REPORT ON THE AMPHIPODA. 187 



genus Dexamine, may well also be an Acanthonotus, but that further information is needed 

 about it. 



After describing the genus Isma with its type species, Isxa montagui, Milne-Edwards, which is 

 figured pi. 29, fig. 11, he passes to Anisopus, with its single species dubius, Tompleton, 

 for which see Note ou Templeton, 1836. 



Accepting the distinction of AmpMtoo from Gammarus as convenient and in general use, though 

 depending only on the absence of the accessory flagelUim from the upper antennse of the 

 former, Milne- Edwards unites under this name the " Ampitoe," Fherusa and Dexamine of 

 Leach. On the other hand he divides and subdivides his own Amphito'e as follows :• — 



" § 1. Especes dont le dos est arrondi et depourvu de grandes dents medianes. 



" A. Thorax et abdomen depourvus d'epines. 



" a. Antennes superieures au moins aussi longues que les antennes inferieures," with the species 

 1. Jurinii, M.-Edw.; figured pi. 1. fig. 2.; 2 leviuscula, Kroyer; 3. Pausilipii, M.-Edw. ; 

 4. indica, j\I.-Edw.; 5. pida, Eathke ; 6. Gaudichaudii, n. s., from Brazil, in which he 

 emphasises the peculiarity " Handle des jjates de la truisieme et quatrihne jxiire ovalaire 

 (au lieu d'etre presque lineaire comme d'ordinaire);" 7. Filosa, Savigny, from which he thinks 

 that " I'Amphitoe de Eamond, and I'Amphitoe des varecs," as he names Pherusa fucicola, 

 Leach, scarcely differ. He gives notes on Gammarus ob.tusatus, Montagu, for which he had 

 already proposed the name Amphito'e ohtitsata ; on TAmphito^ rouge, that is, the Gammarvs 

 rubricaius of Montagu, or Amphitoe rubrioata of Leach ; and lastly on I'Amphitoe dentele, 

 Say's fresh-water Amphitoe deniata. 



" aa. Antennas superieures moins longues que les inferieures. 



"act*. Mains des deux premihres paires d, peu prh de meme grandeur" with the species, 

 " 8. Crenidata," Kroyer ; 9. inermis, Kroyer, to which he appends a note, " Onisais cicada ? 

 Oth. Fabricius, Fauna Groenl. p. 258,"; 10. " Armorica," M.-Edw,; 11. "Eeynaudii," 

 M.-Edw.; 12. " Swaminerdamii," M.-'Edw.; 13. punctata, &aj. 



" aa**. Mains des pates de la seconde paire plus de deux fois aussi grosses que celles des pate-s- 

 anterieures," with the species 14. " Prevostii," M.-Edw.; 15. pelagica, M.-Edw.; 16. 

 " Gaimardii," n. s., which Dana transferred to Allorchestes Gaimardii?, and for which 

 Spence Bate adopts the name Allorchestes Gaimardii, making Allorchestes compressa, Dana, 

 a synonym of it ; 17. pontica, with Hyale pontica, Eathke, for a synonym. 



" AA. Cotes du, thorax ou ledossus de Vabdomen, garnis d'epines ou de petites dents. 



" AA*. Des Spines sur lesflancs." 



18. cancella, the 07iiseus cancellus of Pallas. 

 " AA**. Fluncs depourvus d'epines." 



19. bicuspis, Kroyer; '20. podura, Miiller's Gammarus podurus ; 21. " Fresnelii, Audouin." 

 " § 2. Especes dont le dos est 2)lus ou mains carene en dessus et armc vers sapartie posterieure de 



grandes dents medianes comprimees et dirigees en arriere. 

 " B. Front depourvu de rostre." 



22. costata. M.-Edw.; 23. hijstrix, the Acanthosoma hijstrix of Owen; 24. Marionis, M.-TLdw.; 



25. " Panojila," Kibyer ; 26. " Canwa^a," Kroyer, followed by the concluding observation 



that Say's Ampihitoe serrata "a le dos dentele comme les especes procedentes, mais paratt 



s'en distinguer par I'existence de trois epines saillantes situees k egale distance I'une do 



I'autre sur le bord infi^rieur de chacune des mains." 

 Crevettb. Gammarus, Fabricius, is thus subdivided : — 

 " § 1. Esphces dont les yeux sunt ovalaires, reniformcs ou lineaires. 

 " A. Bord posterieur des trois premiers segmens de Vabdomen droit et ne se prolongeant pas de 



maniere a former une grosse epine ou dent mediane. 

 " a. Des epines sur la p'ortion dorsale da quatr&me et du cinquihme anneaux abdominaux," with 



the species, 1. locusfa, referred to Oniscus pulex ? 0. Fabr., Cancer Gammarus locusfa, 



