184 



exceeding the lengtli of tlio hody, podunolpf! of both clothfd, on their opposite 

 edges, witli mimeroxis traiisvei'se rows of short sensitive liairs, flagella extremely 

 slender and nearly naked. Anterior gnathopoda a little stronger than the 

 posterior ones, with the propodos oblong oval, and considerably shorter than 

 the carpus ; that of the jiosterior ones much narrower, and slightly tapering 

 distally. Anterior pairs of pereiopoda with the propodal joint rather narrow, 

 and considerably longer than tlie carpal j<iint, dactylns slender, and somewhat 

 exceeding the length of the IVirmer. The 2 succeeding pairs with tlie liasal 

 joint much less broad than long, and having the anterior edge evenly curved, 

 and fringed with ciliated setije, carpal joint with about (i transverse rows of 

 spinnles on its outer side, dactjdus comparatively short. Last pair of pereio- 

 poda with the posterior expansion of the basal joint reaching considerably 

 beyond the meral joint and nearly transversely truncated at the tip, inferior 

 and anterior edges defined by an obtuse angle, carpal joint fully as long as 

 the 2 preceding joints combined, and having a row of about D slender spines 

 along the anterior edge, propodal joint a little shorter. Last pair of uropoda 

 with tlie rami sharply pointed at the tip, their opposite edges finely serrated, 

 and having near the base a projecting corner, inner ramus witli 8 denticles 

 on the inner edge. Telson rounded, nearly as long as it is broad, with a few 

 marginal hairs, and two somewhat longer bristles at the tip, incision very 

 short, rounded at the bottom. Body whitish, pellucid, with faint orange- 

 coloured shadows, frontal part of the eeplialon densely mottled with dark 

 violet. Length of adult female 15 mm, of male somewhat less. 



BemarJcs. — This form was first recorded by Kroyer as an Ampelisca, 

 and was figured in the well known work oi«G-aimard, as Ampelisca Gaimardii. 

 Li the year 1870 Boeck, however, ju.stly separated it from that genus, and 

 established the genus Byilis for its reception. It may thus Ije regarded as 

 the type of the present genus. The Byhlis serrata of Smith, of which species 

 I have had a specimen for examination, kindly sent to our Museum, from that 

 author, is very nearly allied to the Kroyerian form, but apparently distinct. 



Occurrence. — The species is a gen\iine arctic form, occurring rather 

 abundantly everj'where off the coast of Finmark, in moderate depths. It also 

 however, extends southwards along the whole west coast of Norway, and is 

 even occasionally met with off the south coast, to the Christianiafjord. 



Distribution. — Arctic Ocean widely distrilnited : (Treenland, Labrador, 

 Iceland, Spitsbergen, the Murman coast, the Kara Sea, the Siberian Polar 

 Sea; Kattegat (Meinert), Bohusliln (Bruzelius) *). 



•) The statement of its opcun-ence also in the IModiteiTanean olT Naples (Costa), ami in 

 the Adriatic (HellerJ, seems to nie very iinestiouable, nml may most probably result 

 from its being confounded witli some nearly allied species. 



