179 



3. Porcellio dilatatus, Brandt. 



(PL LXXVIII, fig. 2.) 

 Pwcellio dilatatus, Brandt & Ratzeburg, Medicin. Zoologie, Vol. II, p. 78, PL 12, fig. 6. 



Syn: Porcellio scaber, M.-Edw. (not Latr.). 



Specific Characters. Body broadly oval, not nearly twice as long as it 

 is broad, dorsal face moderately convex, and rough owing to rounded elevated tu- 

 bercles, especially densely crowded in the middle of the segments. Cephalon with 

 the lateral lobes large, obtusely truncated at the tip, frontal lobe distinctly pro- 

 jecting, obtusely triangular. Side-plates of mesosome rather large, with the 

 posterior corners obtusely acuminate. Metasome nearly twice as broad as it is 

 long, and scarcely attaining ] / 4 of the length of the body, epimeral plates of 3rd 

 to 5th segments greatly prominent, semilimar; last segment nearly as long as it 

 is broad at the base, outer part considerably produced and plane above, tip ob- 

 tusely rounded. Antennae rather strongly built, 2nd joint of the peduncle much 

 dilated, flagellum shorter than the last peduncular joint, and having its articula- 

 tions subequal in length. Legs comparatively short and thick. Opercular plates 

 of the 2 anterior pairs of pleopoda with air-cavities. Uropoda with the outer 

 ramus rather broad, inner ramus scarcely extending beyond the last caudal seg- 

 ment. Colour of dorsal face dark slaty grey, the segments of mesosome ex- 

 hibiting on each side of the median line an assemblage of irregular, somewhat 

 lighter patches. Length of adult female 14 mm. 



Remarks. Though rather nearly allied to P. scaber, with which it was 

 confounded by M. -Edwards, this form may be easily recognized by its unusually 

 broad body, and by the shape of the last segment of the metasome. 



Occurrence. A well-marked adult specimen of this form, the one here 

 delineated, was sent to me from conservator Storm, who found it in a garden 

 hot-house in Trondhjem. I have myself taken 2 not yet fully grown specimens 

 in the Botanical Garden in Christiania, likewise from a hot-house. It is slower, 

 in its motions than most other species. 



Distribution. Denmark, Germany, Poland, Holland, Britain, France, 

 Triest, New Guinea, Australia. 



