47 



of last segment much larger than in female. Caudal segments coarsely spinulose 

 both dorsally and ventrally. Antenna; and legs exhibiting the usual transforma- 

 tion. Pleopoda of the structure characteristic of the genus. Uropoda much more 

 elongated tlian in female, inner ramus with numerous small ciliated spinules inside. 

 Telson exhibiting the usual abrupt bend at about the middle, distal part very 

 narrow. Colour uniformly greyish white. Length amounting to 14 mm. 



h'i'inii rL*. This form was briefly noticed in the year 1863 by the late 

 A. Boeck as a new species of the genus Cwma. The same species was subsequently 

 recorded by Dr. Danielssen as Diastylis Jrispinosa Stimpson, and I myself likewise 

 at first believed it to be identical with the North American form. Having, 

 however, subsequently had an opportunity of examining the latter, I found that 

 both . forms, though nearly allied, were evidently specifically distinct. It is an 

 easily recognizable species, at least in the female sex, being highly distinguished 

 by the strong horn-like processes projecting on each side of the frontal lobe of 

 the carapace. The adult male, as usual, looks so very different from the female, 

 that it is not easy at once to recognize its true relation, whereas in the young, 

 not yet sexually mature state the males closely resemble the females, both as to 

 the general form of the body and the armature of the carapace. 



Occurrence. This is one of our most common species, being found rather 

 abundantly along the whole south and west coasts of Norway, and northwards at 

 least to the Lofoten Islands. It is, however, a true deep-water form, only occur- 

 ring in greater depths, from 50 to 300 fathoms, especially where the bottom con- 

 sists of loose mud and clay. Owing to its spiny armature, the body is often so 

 thickly covered with muddy particles, that it is rather difficult at once to recog- 

 nize its form exactly. Adult male specimens are, as usual, only found quite 

 occasionally. They are much more agile than the females, swimming about with 

 great speed by the aid of their powerfully developed exopodites and pleopoda. 

 The females, on the other hand, generally dwell on the bottom, burying them- 

 selves more or less deeply in the loose mud, and only seldom making a short 

 swimming trip through the water. 



Distribution. Kattegat (Meinert), British Isles (Sp. Bate), coast of France 

 (Fischer), Stat. 21 of the Porcupine Expedition (Norman). 



