Canon A. M. Norman on British Isopoda. 436 



are closer together and even touch each other, but tliat there 

 is considerable variation is evidenced even by Schiodte and 

 Meinert's figures of the male and female. 



2. Rocinela Dumerilii (Lucas). 



1845. Acherusia Dumerilii, Lucas, Anim. Artie. d'Algerie, Crustacds, 



p. 79, pi. viii. fig. 5 *. 

 18G4. Acherusia complanata, Grube, Die Insel Lussin und ihre Meeres- 



fauna, p. 76. 

 1866. Achentsia Dumerilii, Heller, Carcinol. Beit. z. Fauna des adriat- 



ischen Meeres, p. 22. 

 1879. Rocinela Dumerilii, Schiodte & Meinert, /. c. p. 391, pi. xii. 



figs. 4-9, 



Near the Eddystone Lighthouse (Plymouth Biol. Lab. 

 1899) ; Adriatic (^lleller, in Mus. Nor.) ; Naples {A. M. N. 

 1887). 



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

 adult male. Schiodte and Meinert describe the " frons " 

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

 medio magno producto " ; this relates to " femina ovigera." 

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

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

 tubercules releves, 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.^' Bchiodte and Meinert say of Lucas's female 

 "sine dubio femina ejus adulta non fuisset, quain ob rem 

 incertum ha^ret; utrum virginem an niarem adolescentem 

 delineaverit.''' They figure the female, and not the male, and 

 that figure of the female represents the front as " tridens/* 

 while their "virgo'Mias "Frons triangula, apice obtuso, 

 supra sequato." These immature specimens of Bocinela 

 Dumerilii may very easily be mistaken for R. danmoniensis. 

 The Plymouth adult male has the central area of the head 

 raised considerably above the level of the eyes ; this raised 

 part is bounded by elevations which fiank 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 t. Bovallius (" New or imperfectly known Lsopoda,'> 

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



* Such is the reference to plate ia the text, but ray copy has only six 

 plates. 



t 1 fail t(j understand Schiodte and Meinert's pi. xii. fig. 5, for there 

 the rostrum is represented as bent downwards. 



