436 Canon A. M. Norman on Brithh Isopoda. 



are closer together and even toucli eacli other, but tliat there 

 is considerable variation is evidenced even by Schiodte and 

 Meinert's figures of the male and female. 



2. Rucinela Dumerilii (Lucas). 



1845. Acherusia Damevilii, Lucas, Anim. Artie. d'Algerie, Crustacis, 



p. 79, [)1. viii. fig. 5 *. 

 18G4. Acherusia comphmata, Grube, Die Insel Lussin und ihre Meerea- 



friuna, p. 70. 

 1860. Achernsia Dumerilii, Heller, Carcinol. Beit. z. Fauna des adriat- 



iscben Meeres, p. 22. 

 1879. Rucinela Dumerilii, ScbiiJdte & Meinert, /. c. p. 391, pi. xii. 



iigs. 4-9. 



Near the Eddystone Lighthouse (Plymouth Biol. Lab. 

 1899) ; Adriatic {Heller, in Mus. Nor.); Naples [A. M, N. 

 1887). 



The Plymouth specimen is of full size, 27 mm. long, an 

 adult male. Schiodte and Meinort describe tlie "frons''^ 

 thus: — ^^ Frons media excavata^ bicarinata,ante tridens, dente 

 medio magno jjroducto " ; this relates to " femina ovigera.^'' 

 Lucas in the generic description writes : — " La tete est petite 

 et termiuee, dans les males, par un front compose de trois 

 tubercules roleves, dont le median est beaucoup plus pro- 

 nonce; dans les femelles, la tete est seulement trianguliforme" ; 

 and in the specific description " capite in medio fortiter 

 impresso.''^ Hchiodte and Meinert say of Lucas's female 

 "sine dubio femina ejus adulta non iuisset, quam ob rem 

 incertum ha^ret; utrum virginem an marem adolescentem 

 delineaverit." Tliey figure the female, and not the male, and 

 that figure of the fennde represents the front as " tridens,^' 

 Avhile their "virgo^'Mias '^ Frons triangula, apice obtuso, 

 supra a^quato.^' These immature specimens of Bocinela 

 Dumerilii may very easily be mistaken for R. danmoniensis. 

 The Plymoutli adult male has the central area of the head 

 raised considerably above the level of the eyes; this raised 

 part is boutided by elevations which flank the eyes on each 

 side, but the central portion between three lateral elevations 

 is much depressed; in front the rostrum projects forwards 

 and is bent upwards, and on each side of this central point 

 are others of the same form and also bent upwards. This 

 exactly corresponds with the description of Lucas of the same 

 sex f. Bovallius ("New or imperfectly known Isopoda/' 

 K. Vet.-Akad. Handl. vol. xi. 1886, p. 9 (separate copy), 



* Sucb is the reference to plate in the text, but my copy has only six 

 plates. 



t I fail to understand Schicidte and Meinert's pi. xii. fig. 5, for there 

 the rostrum is represented as bent doirnwarch. 



