16 G. O. Sais. 



single natatory seta issuing from the inner edge, whereas 

 the last joint carries 6 such setæ, 3 of which originate from 

 the inner edge, 2 from the tip, and one from the outer edge. 



The 3 succeeding pairs (see fig, 12) are all of essentially 

 the same structure, though they increase somewhat in length 

 posteriorly. Both rami are distinctly 3-articulate ; but the 

 inner one is considerably shorter than the outer. Each joint 

 of the latter carries outside a strong denticulated spine, and 

 the last joint has, moreover, at the tip a much larger, sabre- 

 shaped spine, densely spinulosa outside, and almost equalling 

 the whole ramus in length. This joint, which is but little 

 longer than the 2nd, and much narrower, carries inside 5 

 natatory setæ, and each of the 2 preceding joints has a single 

 such seta. Of the joints of the inner ramus the 1st has 

 only one, the 2nd 2, and the last 7 natatory setæ, 2 of which 

 issue from the outer edge. 



The last pair of legs (fig. 13) look very different from 

 the preceding ones, but are in reality composed of the same 

 chief parts. They are, on the whole, built upon the same type 

 as in the genus Diaptomus, though they are comparative!}'' 

 more robust. The 2 joints composing the basal part are 

 very sharply defined and movably connected with each 

 other, the distal one being conspicuously constricted at the 

 base and of triangular shape. They are both quite devoid 

 of setæ or spines. The outer ramus is about the length of 

 the basal part and rather thick, being composed of 2 joints 

 only, the 1st of which is of considerable size and widens 

 slightly distally, but without any appendages. The last 

 joint is quite short, and terminates in 3 diverging spines of 

 moderate size. Of these spines the innermost and largest 

 forms the immediate prolongation of the joint, and answers 

 to the terminal claw in Diafptomiw. The 2 other spines are 



