1S1 



patches may be plainly seen, and in male specimens, as a rule, the median row 

 is also easily distinguishable. 



Occurrence. In the neighbourhood of Christiania, this is one of the com- 

 monest Oniscoida, being found rather plentifully, not only within the limits of 

 the town, but also at rather great distance from it, on open fields beneath stones 

 and pieces of wood. I have also taken it at Drobak and Skien, and have re- 

 ceived specimens collected by Mr. Ellingsen at Fredrikstad and Kragero. It is 

 rather active, and when disturbed, runs away at once to conceal itself, but it is 

 not nearly so rapid in its motions as P. pictus, to which it bears some resem- 

 blance in its variegated markings. 



Distribution. Northern, western and middle Europe, everywhere; Trans- 

 caucasia, North America. 



5. Porcellio laevis, La.tr. 



(PI. LXX1X, fig. 2.) 

 Porcellio Iceris, LaireiJle, Hist. nat. des Crust. & Insectes. Vol. VII, p. 4H. 



Syn: Porcellio Degeerii, And. & Savign. 



eucercus, Brand i. 



syriacus, Brandt. 



niusculuft, Brandt. 



cinerasceiis, Brandt. 



flubius, Brandt. 



Poeyi, Guerin. 



wbicus, Koch. 



flaripes, Koch. 



cubensis, Sauss. 



sumichrasti, Sauss. 



cotillce, Sauss. 



aztecus, Sauss. 



mexicamis, Sauss. 



Specific Characters. Body oval, greatest width slightly exceeding half the 

 length, dorsal face moderately convex and almost perfectly smooth. Cephalon 

 with the_ lateral lobes well developed, rounded, frontal lobe obtusely triangular. 

 Side-plates of mesosome subcontiguous, 1st pair considerably larger than the suc- 

 ceeding ones, which have the posterior corners but slightly produced. Metasome 

 not nearly attaining y 4 of the length of the body, epimeral plates of 3rd to 5th 

 segments of moderate size and slightly recurved ; last segment subtriangular, outer 

 part acutely produced and slightly grooved above. Antennae very slender, equal- 

 ling half the length of the body, tiageHum not attaining the length of the last 

 peduncular joint, and having the proximal articulation somewhat longer than the 

 distal one. Last pair of legs differing but little in the two sexes. Opercular 



