161 



pleopoda in male greatly produced; Inarticulate; that of 2nd pair of different 

 structure in the different species. Uropoda with the basal part rather broad and 

 flattened, both rami terminating in a pencil of delicate hairs. 



Remarks. — This genus, established by J. F. Brandt, forms the type of 

 the family Trichoniscidw, and may chiefly be distinguished from the other genera 

 by the distinctly developed, though small eyes, the narrow metasome, and the 

 delicate hair pencils in which the antennas and both rami of the uropoda term- 

 inate. The genus comprises as yet 5 or 6 species, 3 of which will be de- 

 scribed below. 



l. Triehoniseus pusillus, Brandt, 



(PI. LXXII, tig. 1.) 

 Jrichoniscus pusillus, Brandt, Conspectus monogr. Crust. Oniscodorum p. 12, PI. 4, fig. 9. 



S_vn: Itea riparia, Koch. 

 ,. Itea Icevis, Zaddach. 

 „ Philougria riparia, Kinahan. 



Specific Characters. — Body oblong oval in form, nearly 3 times as long 

 as it is broad, dorsal face rather convex and quite smooth and polished. Cephalon 

 with the lateral corners very small, though distinct, front obtusely rounded. 

 Lateral parts of the 4 anterior segments scarcely at all expanded; those of the 

 3 posterior segments more prominent and recurved, terminating in acuminate 

 corners. Metasome occupying about y 4 of the length of the body, and rather 

 narrow, with the epimeral plates small and appressed; last segment with the 

 terminal expansion rather broad, and slightly emarginate at the tip. Antennulse 

 with the last joint longer than the 2nd, and carrying 6 sensory filaments, one 

 of which is smaller than the others and somewhat remote from the tip. An- 

 tenna? attaining to about x / 3 of the length of the body, joints of the peduncle very 

 distinctly defined, and each carrying at the end inside, one or 2 slender spines, 

 flagellum a little longer than the last peduncular joint, and composed of 4 arti- 

 culations. Uropoda with the outer ramus fully twice as long as the basal part, 

 inner ramus somewhat shorter and much narrower. Colour of dorsal face dark 

 reddish brown, with numerous irregular lighter specks. Length of adult female 4 mm. 



Remarks. — This is the first described species, and may accordingly be 

 regarded as the type of the genus. It is easily recognized from the 2 other 

 northern species by its dark reddish brown colour, and the smoothness of the 

 dorsal face. The Itea riparia of Koch, as also the Itea Icevis of Zaddach, are 

 undoubtedly identical with this species. Mr. Max Weber describes a small variety 

 from Holland as var. balava, which may be a distinct species. 



21 — Crustacea. 



