539 



make a satisfactorily distinct definition of these 3 groups separately, I have 

 preferred to combine them in one family, which may more properly be named after 

 the genus first established, viz, that of Plwtis Kroyer. It is chiefly distinguished 

 from the Gammaridffi by the structure of the last pair of uropoda, and that 

 of the telson, which latter exhibits a more or less distinct tubular shape, on 

 account of its receiving within it the terminal part of the intestine. Some of 

 the forms pertaining to this family are stated to construct abodes in which 

 they take shelter, thus approaching in their habits the true domicolous 

 forms belonging to the 2 succeeding families. The present family comprises 

 10 Norwegian genera. 



<ien. i. Microdeutopus, Costa, is:,:; 



Syn : Lembos, Sp. Bate. 



Autonoe, Bruzelius (part). 



Body slender and but little compressed, with the coxal plates compa- 

 ratively small, 1st pair produced in front, especially in the male, 4th pair 

 not emarginated posteriorly. Epimeral plates of metasome comparatively 

 small, and scarcely produced at the lateral corners. Eyes distinct, though 

 rather small. Superior antennae much longer than the inferior, and provided 

 with a distinct accessory appendage. Anterior lip rounded; posterior lip 

 rather large, with distinctly developed inner lobes, outer lobes produced laterally 

 to an acuminate lappet. Mandibles strong, with the palp of moderate size 

 and having the terminal joint attenuated. First pair of maxilla 3 with the 

 basal lobe small, unisetose; 2nd pair with the lobes rounded. Maxillipeds 

 with both the basal and masticatory lobes well developed, palp not ver\ 

 large. (Inathopoda in female comparatively small, the anterior ones being 

 a little larger than the posterior, and having the propodos imperfectly 

 subcheliform; propodos of the posterior ones rather narrow, with the palm 

 nearly transverse, and very short. Anterior gnathopoda in male greatly 

 developed, with the carpus extremely large and swollen, being more or less 

 produced in front, so as to form together with the propodos and dactyl us a 

 kind of chela. The 2 anterior pairs of pereiopoda of moderate size, and 

 exactly alike; the 3 posterior pairs rapidly increasing in length, and having 

 the basal joint but little expanded. Branchial lamella- simple; incubatory 

 lamellae large and broad. Last pair of uropoda. not extending beyond the 

 others, basal part somewhat dilated interiorly, rami sublinear, and sparsely 



