163 



molar expansion large and protruding; between both a dense series of curved 

 spines ; palp slender, setous. Maxillae well-developed, and of normal structure. 

 Maxillipeds having the basal part fringed with long ciliated setae, masticatory 

 lobe large, and armed on the inner edge with strong laminar spines, palp not 

 very large, densely setous, with the penultimate joint short and thick, ter- 

 minal joint unguiform. G-nathopoda comparatively feeble in structure and 

 imperfectly subcheliform, the posterior ones, as a rule, more slender than the 

 anterior. The 2 anterior pairs of pereiopoda somewhat unequal in size, meral 

 joint very large and fringed with ciliated seta? more numerous on the 2nd 

 pair, dactylus long and slender. The 2 succeeding pairs recurvate, basal joint 

 large and muscular, carpal joint elongated, and forming at the end posteriorly 

 a projecting corner, dactylus very small, and turned posteriorly. Last pair 

 of ,'pereiopoda very unlike the preceding ones and much shorter, basal joint 

 more or less expanded and forming posteriorly a deflexed lobe fringed with 

 ciliated seta?. Branchial lamella? transversely plicated; incubatory lamellae 

 very narrow. Pleopoda well-developed. The 2 anterior pairs of uropoda nor- 

 mal; last pair with both rami uniarticulate, and more or less foliaceous, in 

 male fringed with ciliated seta?. Telson more or less deeply cleft. 



Remarks. This family has been removed by Boeck far from the 

 preceding ones, and was placed by him immediately in front of the Photidtr. 

 In doing so he was probably induced by the fact, that some of the forms 

 belonging to the present family are found to construct themselves tubes for 

 dwelling in, as is the case with several of the more sedentary forms, which 

 have been comprised within the division Domicola of Sp. Bate. As, however, 

 the divisions Vagantia and Domicola of the latter author, are now generally 

 rejected by modern authors, since there are many forms among the latter 

 division which do not at all construct tubes, it will be best wholly to abandon 

 this feature as a systematical criterion, and to tix our attention chiefly on the 

 structural affinities. In doing so, we shall certainly find that the family in 

 question more properly keeps the place to which it was originally assigned by 

 Sp. Bate, viz., immediately after the Pontoporciidce and Pln>.iid'. In fact, tin- 

 above described genus Argissa, referred by Boeck, without any hesitation, to 

 the Pontoporeiidce, forms a most obvious connecting link between that family 

 and the one here spoken of. Setting aside the latter genus, all the forms com- 

 prised in the present family exhibit a very characteristic and easily recogniz- 

 able appearance, by their smooth, more or less curved body, the peculiarly 

 constructed visual organs, the slender setous antenna', and the characteristic 

 structure of the pereiopoda. The family comprises, as yet, but 8 genera, all of 

 which are represented in the fauna of Norway. 



