177 



the posterior corners acutely produced. Metasome occupying about x /4 of the 

 length of the body, epimeral plates of 3rd to 5th segments strongly recurved; 

 last segment rather produced, terminating in an acute point slightly grooved 

 dorsally. Antenna? less slender, scarcely attaining half the length of the body, 

 flagellum about as long as the last peduncular joint, and having its 2 articulations 

 of nearly equal size. Last pair of legs differing but little in the two sexes. 

 Opercular plates of only the 2 anterior pairs of pleopoda with air-cavities. Uro- 

 poda with the outer ramus broadly lanceolate, and comparatively larger in male 

 than in female. Colour of dorsal face generally a uniformly greyish black; some- 

 times, however, lighter, and variegated with irregular dark patches, more rarely 

 black, with the side-plates light yellowish. Length of adult female 14 mm. 



Remarks. Of all our Oniscoida, this is perhaps the commonest' and 

 most widely distributed species. I have taken it rather abundantly around Chri- 

 stiania, especially in refuse-heaps. At Drobak it is also very common, both in 

 the town and at some distance from it, beneath stones on the beach. Further- 

 more, I have taken it at Skien, and at Sauesund, west coast of Norway. In the 

 latter place it occurred near the shore, just above high-water-mark, beneath decaying 

 alga3, and in company with Ligia oceanica. According to conservator Storm, it 

 is also common at Trondhjem, and last summer conservator Sig. Thor collected 

 it on one of the Lofoten Islands. Finally, I have received from conservator 

 Schneider a few specimens of this species taken in Finmark from a Laplanders 

 turf-hut. The variety marmorata is found occasionally both here in Christiania 

 and at Drobak together with the typical form, and more rarely also the var. 

 marginata, in which the dark back is flanked by a broad light yellow border oc- 

 cupying the side-plates of the mesosome. The animal is rather agile, running 

 away with considerable speed, when disturbed, to conceal itself. 



Distribution. Northern, western and central Europe everywhere, south 

 Europe less frequent, Iceland, Greenland, North America, Mexico, islands St. 

 Paul, St. Croix and Ascension, Kamtschatka, Cape of Good Hope. 



2. Poreellio pictus, Brandt. 



(PI. LXXVIII, fig. 1.) 

 Poreellio pictus, Brandt & Ratzebm-g, Medicin. Zoologie, Vol. II, p. 78, PI. 12, fig. 5. 



Syn: Poreellio melanocephahts, Koch. 

 mixtus, Fitch. 



Specific Characters. Body oblong oval, and considerably depressed, with the 

 face rough owing to the presence of small elevated tubercles, less densely crowded than 

 in P. scaber. Cephalon with the lateral lobes very large and slightly curved out- 



23 Crustacea. 



