75 



biarticulate, and carrying 2 seta? at the tip. Uropotla moderately slender, outer 

 ramus about the length of the stem, inner ramus considerably longer, with about 

 10 spinules inside, apical spine rather strong. Telson semicircular, with 3 slight 

 serrations on each side. Body more or less richly ornamented with ;i dark brown 

 pigment. Length scarcely exceeding 4 mm. 



Adult male considerably more slender than the female, and having the 

 anterior division less vaulted above. Carapace more flattened, and with the 

 pseudorostral projection less prominent. Eye larger, with the visual elements 

 more distinct. Basal joint of the 4 anterior pairs of legs greatly dilated; termi- 

 nal joint of 2nd pair with a single apical hook. Anterior pleopoda with 4 strong 

 setae inside the basal part; posterior pair with 2 slender spines outside the tip. 

 Uropoda more slender than in female, stem with 4 slender setse inside, inner 

 ramus rather produced, and armed inside with about 14 spinules. Telson fully as 

 long as it is broad at the base, edges unarmed. 



J\emarks. As mentioned above, this form was first recorded by P. v. 

 Beneden as a species of the genus Leucon; but both the description and the 

 figures given are rather unsatisfactory, and on this account I did not at first 

 recognize its identity with the Norwegian form, but described the latter as a new 

 species under the name of P. bistriata. The Cyrianassa lonyicornis of Sp. Bate 

 may perhaps be the male of this species, and if so, the specific name longicornis 

 has really priority in date to that proposed by P. v. Beneden. This name, however, 

 would, be rather inappropriate, as it only refers to the one sex, and even there 

 is far from being significant. The Cuma bdla of Meinert is unquestionably the 

 female of this species. The form described by the present author from the Medi- 

 terranean as P. cercaria. differs slightly from the Norwegian form ; but the diffe- 

 rences do not seem to me to be great enough to warrant a specific distinction. 



Occurrence. I first found this form off the Lofoten Islands, where it is 

 very common in the shallow sounds and bays around the fishing stations. Sub- 

 sequently I have also met with it in several other places on the Norwegian coast, 

 from the Christiania Fjord to Vads0, though nowhere in such abundance as off 

 the Lofoten Islands. It generally occurs in comparatively shallow water, on a 

 bottom composed of fine sand covered with a thin layer of blackish mud. Some- 

 times it is even found on the beach in pools left by the tide. It is a very active 

 little animal, being almost constantly in motion, now swimming about through the 

 water, now burrowing in the sand, and twisting its slender tail in all directions. 

 Adult males are not infrequently found together with the females and, as usual, 

 are still more agile and less confined to the bottom. 



