92 G. 0. SARS. CRUSTACEA. [NORW. POL. EXP. 



the concave edge with small compressed denticles, similar to those represented 

 by Dr. Giesbrecht in A. longicaudatua. 



The posterior maxillipeds (fig. 7) are nearly twice as long as the ante- 

 rior, and have the 1st basal joint a little shorter, but broader than the 2nd, 

 with 2 slight prominences anteriorly, each carrying 3 unequal setae. The 2nd 

 basal joint is of about uniform breadth throughout, and carries 2 setae in the 

 middle of the anterior edge, and at the end 2 other setae originating from a 

 separate lobe. The terminal part is considerably shorter than the 2nd basal 

 joint, and is composed of only 4 articulations. The setee issuing from this 

 part are of moderate length, and exhibit a similar structure to those of the 

 anterior maxillipeds. 



The legs (PL XXVI, fig. 5, PL XXVII, figs. 8, 9), are, on the whole, 

 constructed upon the same type as in Heterochceta, all 5 pairs being nata- 

 tory, and having both rami distinctly 3-articulate. On a closer comparison, 

 however, some well-marked differences may be found to exist. They are, on 

 the whole, far less powerful than in Heterochceta, especially as regards the 

 3 middle pairs. In the 1st pair (fig. 8), the spine issuing outside the 1st 

 joint of the outer ramus is very much elongated, and setiform, whereas those 

 of the 2 succeeding joints are extremely small. The relative length of the 

 two rami, as also the number of spines and natatory setee issuing from them, 

 is the very same as in Heterochceta; but both rami are comparatively nar- 

 rower. This is still more the case with the middle pairs (fig. 9), the outer 

 ramus of which is much less dilated, with the terminal joint scarcely as long 

 as the other 2 combined, and not at all foliaceous in character. The 3 spines 

 of the outer edge in this joint are very small, whereas the apical spine is 

 rather slender and elongated, finely spinulose on both edges, and exhibiting 

 a slight curvature inwards. The natatory setae, too, are quite normally 

 developed. 



The last pair of legs (PI. XXVI, fig. 5), though natatory like the preceding 

 ones, differ from them rather conspicuously, both in their smaller size, and 

 in some peculiarities analogous to those found in Heterochceta. Thus the 

 1st basal joint is without the plumose seta present on the inside of the other 

 pairs. On the other hand, the 2nd basal joint has attached to the outer corner a 

 very slender and elongated bristle, not found in the other pairs, and extending 

 downwards along the outer ramus almost to its end. This bristle, which is 



