_ 30 



the Norwegian coast. The species arc ratlin- difficult to distinguish from one 

 another, en accnimt of their rather uniform external appearance, and the ge- 

 nerally small size and inconspicuous colour of the animal. Two of the best 

 distingishing characters arc undoubtedly the structure of the last pair of legs and 

 the relative length of the set:e with which they are fringed. In these characters 

 there are scarcely two species which fully agree with each other. All the species 

 have in common the peculiarity that the specimens remain floating on the surface 

 of the \\ater. when they come in contact with it. a circumstance which essentially 

 facilitates the collecting of them from any mud brought up by the aid of the dredge. 



M. Ectinosoma Sarsi, Boeck. 



ll'l. XVI). 



Sarsii, r->-k. N;. M.-'-^-ter og Arter af SultvaiulseopriMxl.-r. Chr. Vid. Selsk. For- 



liaudl. 1872, ].. l.\ 

 Syii: EctinOSOma .-/'/'///'/'ex. linuly. 



Sj,,,-i(ir Characters. Female. Body somewhat robust, fusiform, greatest 

 width excelling '/ 5 of the length, and occurring somewhat in front of the middle. 

 Cephalic segment about equalling in length the 3 succeeding segments combined, 

 r<tral plate evenly rounded at the tip. Urosome only slightly exceeding in length 

 the exposed part of metasome, posterior edge of the segments densely fringed 

 with delicate spinules. Caudal rami comparatively short, scarcely longer than the 

 last segment, apical setse not much elongated, the innermost but one about equal 

 in length to the urosome exclusive of the caudal rami. Anterior antennae short 

 and thick .~i-articulate. Posterior antennae with the outer ramus almost as long 

 as the inner, middle joint very small. Anterior lip with an acute recurved process 

 in front. Natatory h gs with the rami rather broad, all the spines coarsely 

 denticulate, setse very strong. Last pair of legs sub-quadrangular in outline, inner 

 expansion of the proximal joint rather narrow and extending almost as far as 

 the distal joint, the latter somc\\liat longer than it is broad, and exhibiting on 

 the lower side, near the base, a transverse row of 4 small denticles, immediately 

 below which a slender bristle is attached; marginal spines of both joints unusually 

 short, not extending beyond the middle of the genital segment. 



Mody of an uniform pale \ello\\ish 1m,., ,,r straw-coloured. 



Lenu'th of adult female reaching to !..")( mm. 



/'' narfa. This is the largest of all the known species, and may more- 

 over in the living state be rer.^iii/ed by its pale yellow colour. The structure 

 of the last pair of le^s i> also characteristic from the unusual shortness of the 



