344 



in front to a very large, somewhat flattened rostrum, jiostantennal corners not 

 projecting. Anterior pairs of coxal plates large and deep, 4tli pair the largest 

 and emarginated in their xxpper part posteriori}^ Antennae rather slender though 

 not much elongated. Anterior lip with the lobes nearly equal and covered 

 with fine hairs. Mandibles having the molar expansion imperfectly developed, 

 palp of moderate length. First pair of maxillae with the masticatory lobe 

 well developed, and armed with elongated spines denticulated on the edge; 

 2nd pair having the outer lobe much narrower than the inner. Maxillipeds 

 with the masticatory lobes rather narrow, and scarcely reaching bej'ond the 

 1st joint of the palp, the latter elongated, with the last joint sim])le, and 

 the dactylus comparatively short. Gnathopoda very powerful, propodos large 

 and oval in form, having the palm very oblique and the hind margin armed 

 with tufts of spines, carpus short but produced inferiorly to a narrow lingui- 

 form lobe. Pereiopoda not very strong, and scarcely increasing in length 

 posteriorly. Telson broadly rounded at the tip. 



BemarJcs. — This genus was established by Sp. Bate as early as in the 

 year 1858 to include an arctic species P. tuhevculatus, which is nearly allied to 

 P. panoplus Kroyer, though apparently distinct. Boeck combined the 2 genera 

 Pleusfes and Paramphithoe, adopting at first the latter generic name, and 

 subsequently the former, which is the older one. In my opinion, however, these 

 2 genera ought to be kept apart, differing, as they do, both in the general 

 external appearance, and also in some anatomical characteristics of apparently 

 generic value. Li addition to the 2 arctic forms mentioned above, Boeck 

 describes a supposed new species as P. parvus; but I am disposed to believe, 

 that this form is only founded on young specimens of P. panoplus, in which 

 the strong tuberculation of the body is far less distinct than in adult speci- 

 mens. A third, evidently distinct species has finally been described by the 

 Rev. Mr. Stebbing from the Challenger Expedition as P. ahyssorum. 



1. Pleustes panoplus (Kroyer). 



(PI. 121). 

 AmpMthoe panoi)la, Kroyer, Gronlands Amphipotler. Kgl. Dauske Vid. Selsk. Afh. 1838, 



p. 270, PI. 2, fig. 9. 

 Syn. : Paramphithoij panopla, Bruzelius. 



Body of very compact form and rather broad, upper face roof-like, 

 with a distinct dorsal keel extending throughout the whole mesosome and 

 metasome, lower edges of the segments of mesosome forming on each side a 

 likewise distinct lateral keel. The 2 anterior segments of metasome produced 

 on each side, near the dorsal face, to a rather large poisteriorly pointing digiti- 

 form projection; last segment of metasome and 1st of urosome having on 



