62 G. 0. SARS. CRUSTACEA. [norw. pol. exp. 



2nd of which is the largest. Some of the setse clothing this part are spini- 

 form, and 2 of those issuing from the 1st joint are considerably longer than 

 the others, and are coarsely ciliated at the base. 



The natatory legs (figs. 5—8) are powerfully developed, and, on the whole, 

 resemble in structure those in the Scolecithricidce. The 1st pair (fig. 5), how- 

 ever, are rather small, as compared with the others, and have the first 2 

 joints of the outer ramus imperfectly defined, being only indicated by the 

 presence of 2 successive spines on the outer edge; of these the distal one is 

 attached to a projecting knob-like expansion of the joint. The inner ramus 

 in this pair is uniarticulate, with the outer edge bulging in the middle. In 

 the 2nd pair (fig. 6) this ramus is distinctly biarticulate, and in the 2 posterior 

 pairs (figs. 7, 8), it is composed of 3 well-defined joints. The outer ramus in 

 the 3 posterior pairs is very large and broad, with the apical spine coarsely 

 serrate outside. The number of natatory setse and spines on the rami is 

 exactly the same as in the Scolecithricidce described above. In none of the 

 pairs, however, could any spinules of the posterior face be detected. On the 

 other hand, the 4th pair (fig. 8) is distinguished by 5 closely-set spines 

 issuing inside the 1st basal joint, immediately above the plumose seta. 



Behind the natatory legs, not the shghtest trace of any limbs could be 

 detected, and indeed, this total absence in the female of the last pair of legs 

 is a character common to ail the forms included in the present family. 



Description of the Adult Male. 



The length of the solitary specimen examined, which seems to be fully 

 grown, is about 6 mm., and the male, accordingly, does not nearly attain the 

 size of the female. 



The general form of the body (see PI. XVI, fig. 1) is rather more slender 

 than in the female, with the anterior division narrow oblong, and having the 

 lateral corners of the last segment less produced. The tail is somewhat more 

 elongated in proportion to the anterior division, and is rather slender, being, 

 as usual, divided into 5 segments, the last of which, however, is so very 

 small, as easily to escape attention. The caudal rami with their apical setse 

 are about as in the female. 



The anterior antennse (fig. 2) appear more slender and attenuated than 

 in the female, and are only composed of 22 articulations, the 8th and 9th 



