163 



basal part. Colour of dorsal face whitish, semipellucid, with a few light brown 

 pigmentary ramifications across the segments, and a double row of irregularly 

 lobular, opaque white patches along the middle of the back, probably caused by 

 some internal matter (renal excretions). Length of adult female scarcely ex- 

 ceeding 2 mm. 



JRemarJcs. — I have not been enabled to identify this form with any of the 

 earlier described species. At first I thought that it might perhaps be the form 

 mentioned by Dr. M. Weber as T. pusillus var. batata: but there are several 

 things which forbid such an identification. For instance, Dr. Weber says that the 

 dorsal face in his form is perfectly smooth and of a similar dark brown colour 

 to that in the type species, and the flagelluni of the antenna; is stated to be 

 4-articulate, not, as in the present species, 3-articulate. 



Occurrence. — I have only met with this form in a single locality in the 

 immediate vicinity of Christiania, but there rather abundantly. It occurred on an 

 open plain, close to the railway, beneath stones and pieces of wood, in company 

 with Trichoniscoides albiclus, to be described below. It is far less agile than T. 

 pusillus, through not nearly so slow in its motions as the just-named form. 



3. Triehoniseus roseus (Koch). 



(PL LXXIII, fig. 1.) 



Itea rosea, Koch, Deutschlands Crust, p. 22, fig-. 16. 



Syn: Philougria rosea, Kinahan. 



Specific Characters. — Body oblong oval, greatest width almost attaining 

 half the length, dorsal face but slightly convex, and rough, owing to numerous densely 

 crowded tubercles arranged in transversal rows. Cephalon transversely oval, with 

 the lateral lobes well-marked, denticulate, front nearly straight. Lateral parts of 

 mesosome more expanded than in the other species, 1st pair rather broad and 

 partly flanking the cephalon, the 3 posterior pairs recurved and acuminate. Me- 

 tasome (in male) exceeding half the length of the mesosome, and but little more 

 than half as broad ; terminal expansion of last segment transversely truncate, 

 with 4 small apical spinules. Antemiulee with the last joint much longer than 

 the 2nd, • and carrying 6 sensory filaments, 5 apical and 1 lateral. Antennae 

 comparatively slender, attaining 1 / s of the length of the body, flagelluni composed 

 of 4 articulations. Last pair of legs in male peculiarly modified, having the 

 meral joint strongly dilated, and produced inside to a large conical prominence, 

 in against which the succeeding joint admits of being bent. Inner ramus of 1st 

 pair of pleopoda in male, with the terminal joint dilated at the end in the form 



