4i2 G. 0. SARS. CRUSTACEA. [norw. pol. exp. 



an attempt at a subdivision. It carries 5 natatory setse, 2 of which issue 

 from the tip, the other 3 from the inner edge. 



The 2nd pair of legs (fig. 5) are much larger than the 1st, and have the 

 outer ramus nearly twice as long as the basal part. The 1st joint of this 

 ramus, however, is comparatively small, and is much constricted at the base, 

 carrying outside a M'ell developed spine, and inside a natatory seta. The 2nd 

 joint is large and expanded, and likewise provided outside with a strong spine, 

 inside with a natatory seta. The last joint is still larger, being fully as long 

 as the other 2 combined, and it carries outside 3 strong spines attached to 

 distinct ledges on the margin, inside, 4 natatory setae, and at the tip an 

 exceedingly strong, mucroniform spine, coarsely denticulate outside. The 

 inner ramus is scarcely more than half as long as the outer, and is composed 

 of 2 well defined joints, the 1st rather small, and carrying inside a single 

 natatory seta, the last oblong fusiform, and provided with 5 natatory setae, 

 2 of which issue from the tip, 2 from the inner edge, and one from the outer. 



The 2 succeeding pairs of legs (PI. VII, fig. 6, PI. VIII, fig. 8) resemble 

 in structure the 2nd pair, but are still larger, and have the inner ramus 

 distinctly 3-articulate, with one natatory seta more than in that pair. The 

 terminal joint of the outer ramus is, moreover, somewhat larger, considerably 

 exceeding in length the other 2 combined. In all the pairs except the 1st, 

 several transverse rows of small spinules are observed on the hind face of 

 the rami. These spinules are especially conspicuous on the inner ramus, 

 ^\'here they are arranged in 3 or 4 oblique rows. 



The 5th pair of legs (PI. VII, fig. 7) are very small and simple in struc- 

 ture, somewhat resembling those in the genus Scolecithrix. They are, how- 

 ever, less rudimentary, each leg being composed of 3 distinct joints, whereas 

 in the above-named genus, these legs are biarticulate, or altogether wanting. 

 The basal joints of both legs are united in the middle, constituting a common 

 broad basal part. The 2nd joint is rather small, but well defined from both 

 the basal and terminal joints. The last joint is oblong fusiform in shape, 

 and carries 3 unequal spines, one apical and 2 lateral. Of the latter, that 

 issuing from the inner edge is very much elongated and extended obliquely 

 inwards, so as to meet the corresponding spine of the other leg. It is finely 

 denticulate outside, whereas the other spines are quite smooth, that of the 

 outer edge being also very small. 



