180 



4. Poreellio Rathkei, Brandt. 



(PI. LXXIX, fig. 1.) 

 Poreellio Rathkei, Brandt, Consp monogr. Crust. Isop. terrestr. p. 15, fig. 10. 



Syn : Poreellio ferrugineus, Brandt. 

 trilineatus, Koch. 

 trivittatus, Lereb. 

 tetramoerus, Schnitzl. 

 striatus, Schnitzl. 

 sylvestris, Schobl. 



Specific Characters. — Body oval, somewhat broader in female than in 

 male, dorsal face rather convex and slightly tuberculated. Cephalon with the 

 lateral lobes well developed, rounded, frontal lobe short, obtusely triangular. 

 Side-plates of mesosome of moderate size, subcontiguous, with the posterior cor- 

 ners obtusely acuminate. Metasome scarcely attaining 1 / i of the length of the 

 body, epimeral plates of 3rd to 5th segments well developed, recurved; last seg- 

 ment subtriangular, outer part acutely produced and plane above. Antenna? rather 

 slender, nearly attaining half the length of the body, flagellum about the length 

 of the last peduncular joint, and having its proximal joint somewhat shorter 

 than the distal one. Last pair of legs in male stronger than in female, with the 

 carpal joint remarkably dilated near the base. Opercular plates of all the pleo- 

 poda with air-cavities. Uropoda with the outer ramus broadly lanceolate, inner 

 extending considerably beyond the last caudal segment. Colour of dorsal face 

 somewhat variable, being in female, as a rule, lighter than in male, with irre- 

 gular- dark patches intermingled with some of a ferruginous hue, and more ge- 

 nerally exhibiting a row of more or less distinct whitish patches on each side of 

 the mesosome, at the base of the side-plates. Colour of male specimens generally 

 dark slaty grey, with 3 longitudinal rows of whitish patches on the mesosome, 

 the one median, the 2 other sublateral, and between these rows on each segment 

 an assemblage of light, wavy stripes. Length of adult female 12 mm. 



Remarks. — This species was first described under the above name by 

 Brandt, but has subsequently been recorded under several other names, that 

 proposed by Koch, trilineatus, having been more generally used. It may be 

 distinguished from the preceding species by its comparatively convex body and 

 the mutual longitudinal relation between the 2 articulations of the antennal fla- 

 gellum. The colour, especially of female specimens, is rather variable, and has 

 occasioned the establishment of several spurious species. In some cases it even 

 changes to a rather uniformly light ferruginous hue, with scarcely any trace of the 

 characteristic sublateral row of light patches. More generally, however, these 



