579 



strongly pi'ominent. Anterior lip rounded; posterior lip having the outer 

 lobes bifid at the tip. Mandibles very sti'ong, with the cutting elge coarsely 

 dentate, palp comparatively short, with the terminal joint large and expanded, 

 being densely setous both at the tip and the inner edge. First pair of maxillae 

 with the masticatory lobe coarsely spinous at the tip, basal lobe small 

 nni-setose, palp of moderate size, with the terminal joint slightly expanded 

 Second pair of maxillae with the outer lobe much larger than the inner. 

 Maxillipeds having the masticatory lobes large and dentate in.side, palp 

 comparativel}' short. Gnathopoda distinctly subcheliform, in female not very 

 strong, in male much more powerful, especially the posterior ones, but 

 otherwise of the same structure as in the female. Pereiopoda rather stout, 

 the 3 posterior pairs siiccessively increasing in length, and having the 

 pro})odal joint simple, basal joint of antepenultimate pair short and broad, 

 that of the last 2 pairs oval in form. Last pair of uropoda with the basal 

 jiart rather massive, rami subequal in length, the outer one lamellar, and 

 armed with 2 recurved hooks, the inner one conical in form. Telson of moderate 

 size, with a .small tuberculiform projection on either side of the tip. 



EemarJcs. — The present genus was established as early as in the 

 year 1813 by Leach, to include the Cancer (Gammarus) ruhricaf lis of Montagu. 

 Boeck quotes as synonj'ms the genera Cymadusa of Savigny and Anisopus 

 of Templeton. In the restriction here adopted, the genus is chiefly 

 distinguished by the long slender body, the strong development of the inferior 

 antennae in the male, the shape of the mandibular palps and the posterior 

 lip, the structure of the gnathopoda in the two sexes, and the form of the 

 telson. Several species have been described as belonging to this genus from 

 difi'erent parts of the Oceans, but it is mo.st probable, that some of these 

 species may more properly be referred to one or other of the 2 .succeed- 

 ing, nearly-related genera. To the fauna of Norway belongs only a single 

 species, to be described below. 



1. Amphithoe rubricata, (Mont.). 



(PI. 206). 



Cancer (gammarus) ruhricafus. Montagu, Linn Trans. Vol. IX, p. 99. 



Syn. : Amphithoe podoceroides, Rathke. 

 J — albomaculata, Kroyei'. 



> — litorina, Sp. Bate. 



Body long and slender, somewhat compressed, and having the back 

 evenly rounded throughout. Cephalon with the frontal part slightly produced 



