104 



length, without any distinctly defined squamiform appendage. Oral parts nearly 

 as in lanira. Legs comparatively short and of uniform structure, the 1st pair 

 not being prehensile in either sex, dactylar joint 3-unguiculate. Middle piece of 

 male operculum considerably expanded at the end. Uropoda extremely small, bi- 

 ramous, rami very short, nodiform. Male smaller than female. 



Remarks. This genus, established by Leach in the year 1813, is chiefly 

 distinguished by the short and flat body, the very small superior antejmre and 

 uropoda, and the uniform structure of the legs. It comprises as yet about 7 

 species, only one of which belongs to the fauna of Norway. 



laera marina (Fabr.). 



(PI. XLIII.) 

 Omscus marinns, O. Fabvicius, Fauna Gronlandic-a, p. 252. 



Syn : laera albifrons, Leach. 

 Eroyeri, Zaddacli. 



laltlca, Fr. Miiller. 



copiosa, Stimpson. 



nil-alls, Kroyer. 



Specific Characters. Pody oval in form, scarcely more than twice as long 

 as it is broad, in male somewhat shorter and stouter than in female, and slightly 

 widening behind, lateral edges of the segments in both sexes fringed with rather 

 short and simple hair-like bristles. Cephalon more than twice as broad as it is 

 long, lateral expansions obliquely truncated, frontal edge slightly Insinuate, obtusely 

 produced in the middle. Caudal segment semicircular in shape, comparatively 

 larger and broader in male than in female, apical notch not very deep. Eyes of 

 moderate size, rounded oval in form. Superior antenna? reaching but little beyond 

 the antepenultimate peduncular joint of the inferior ones, flagellum very small, bi- 

 nrticulate. Inferior antennae about the length of the body, not including the cau- 

 dal segment, outer appendage of the peduncle replaced by a simple spine, fla- 

 gellum fully twice as long as the peduncle. Legs but slightly increasing in length 

 posteriorly, one of the 3 dactylar claws rather small, and somewhat removed from 

 the tip. the other 2 strongly curved. Female operculum semicircular; middle 

 piece of male operculum forming at the end, on each side, a rather large expan- 

 sion terminating in a hook-like, anteriorly-curving point. Uropoda projecting 

 somewhat beyond the apical notch of the caudal segment, both rami well defined, 

 though very small, and tipped by a fascicle of bristles, the inner one about half 

 the length of the basal part, the outer considerably smaller. Body more or less 

 thickly dotted with dark brown, sometimes uniformly blackish or variegated with 

 large whitish patches. Length of adult female 4 mm., of male 3 mm. 



