436 Canon A. M. Norman on British Isopoda. 



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

 is considerable variation is evidenced even bj Schibdte and 

 Meinert's figures of the male and female. 



2. liocine/a Dumeriln (Lucas). 



1845. Acherusia DumeriUi, Lucas, Auim. Artie. d'Algt^rie, Crustac^3, 



p. 70, |)1. viii. fig. 5 *. 

 18(54. Acherusia complonata, Grube, Die lusel Lussin und ibre Meeres- 



fauna, p. 70. 

 1866. Acherusia DumeriUi, Heller, Carciuol. Beit. z. Fauna des adriat- 



iscbea Meeres, p. '22. 

 1879. Rociuela DumeriUi, Scbiiidte & Meinert, /. c. p. 391, pi. xii, 



figs. 4-9. 



Near the Eddystone Lighthouse (Plymouth Biol. Lab. 

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



1887;. 



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

 adult male. Scliibdte and Meinert describe the " frons " 

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

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

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

 et terniinee, 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 seulcment trianguliforme'^ ; 

 and in the specitic description " capite in medio fortiter 

 impresso.^^ ^schio.lte and Meinert say of Lucas's female 

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

 incertum luvret; utrum virginem an marem adolescentem 

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

 tliat figure of the female represents the front as " tridens/' 

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

 supra ffiquato." These immature specimens of Rocinda 

 DumeriUi 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 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. Yet.-Akad. Handl. vol. xi. 1886, p. 9 (separate coj)y), 



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

 plates. 



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

 the rostrum is represented as bent doicmoards. 



