152 TEANSACTIO'NS LIVEEPOOL BIOLOGICAL SOCIETY. 



species but shorter and stouter. Inner branches of the 

 first pair of swimming feet slender and of moderate 

 length, basal joint nearly as long as the entire outer 

 branch, and furnished with a plumose seta arising from 

 the lower half of the inner margin and extending to 

 slightly beyond the end of the branch, second joint fully 

 two-thirds the length of the basal joint also furnished 

 with a plumose seta arising from near the middle of its 

 inner margin, third joint very small, bearing on its apex 

 two stout spines and one short plumose seta ; outer 

 margins and proximal halves of the inner margins of the 

 first and second joints fringed with short hairs, the joints 

 of the outer branches are short and broad, the second 

 joint is slightly shorter than the first and the third joint a 

 little shorter than the second, the armature of the joints 

 is somewhat similar to that of the first pair in Idya 

 furcata ; the spines are furnished with a row of moderately 

 long cilia on the upper margins. Second, third and fourth 

 pairs of swimming feet similar to those of Idya furcata. 

 Fifth pair of feet very short being little more than half 

 the length of the joint to which they are attached and 

 extending only a little way beyond the base of the first 

 segment of the abdomen, the length of each foot is about 

 equal to twice the breadth, the secondary joint is furnished 

 with three setae on the apex, the innermost one being 

 longer than either of the other two, outer very short ; a 

 short seta is attached to the outer margin a. little way 

 from the apex. Caudal stylets narrow and slightly 

 divergent, length equal to about twice the breadth and 

 nearly as long as the last segment of the abdomen. 



Male. Antennules nine-jointed, hinged between the 

 third and fourth joints and also between the seventh and 

 eighth joints, fourth joint very small ; the other appendages 

 are similar to those of the female, fifth feet also similar to 

 the fifth feet of the female but smaller, 



