The second and third legs carry well developed exopods, that of the second equal in 

 size to the exopod of the first leg, while that of the third is slightly smaller. The fourth and 

 fifth legs are without any trace of exopods. 



The second legs have the basis about four-fifths the length of the remaining segments. 

 The ischium is distinct though very short. The carpus is a little longer than the merus and bears 

 at its distal end a group of long and stout spines. The dactylus is half as long again as the 

 carpus, rather slender, and well armed with lateral and terminal spines. The three posterior 

 legs diminish successively in length. The third pair have the basis longer than the remaining 

 segments together, while in the fifth pair it is only about "/^ of that length. The carpus is in 

 each case a little longer than the merus. The legs are abundantly beset with plumose hairs 

 and the carpus bears distally a group of stout flexible annulated setae. 



The pleopods are large and well provided with natatory setae. The rami of the first 

 pair are about two-thirds the length of the peduncle. 



The uropods (PL I, fig. 12) are long and slender. The peduncle is more than I'/j times 

 the length of the last somite and is beset on its inner edge with numerous short spinules and 

 a few setJE. The exopod is nearly two thirds the length of the peduncle, the endopod a little 

 shorter. The first segment of the endopod is longer by one half than the second; the inner 

 margins of both segments are beset with numerous slender spinules of unequal length and the 

 outer margins of both carry series of short setae; the terminal spine is very slender. The first 

 seo-ment of the exopod is about two-thirds the length of the second, measured along the 

 outer edo-e. The inner margin of the first and both margins of the second segment are clothed 

 with setae. 



Occurrence. Station 211, 1 1 5 8 metres, i specimen. 



Remarks. This species adds another to the somewhat puzzling group of forms which 

 appear to establish a transition between the Bodotriidce and Vauntompsoniida. Miers defines 

 his genus Heteroacma (P. Zool. Soc. London, 1879, p. 57) as having the "first three pairs of 

 leo-s palpigerous in both sexes" but the figure of the male which accompanies his paper shows 

 exopods on all the legs. Without commenting on this discrepancy. Stebbing (Hist. Crust, 

 p. 304) refers the genus to the VanntompsoniidcE, defining the family as having, in the male 

 sex, "well-developed swimming-branches" on the first four legs. On examining the type-specimens 

 of H. Sarsi, I find that (as Hansen appears to suspect, Isop, Cumac. Plankton Exp. p. 56). 

 Miers' text was right and his figure wrong in this respect, the male resembling the female in 

 having exopods on the first three legs only. Those on the second and third legs are, as 

 described in the female by Hansen, quite small, unsegmented rods, without flagellum. In the 

 number and character of the exopods present in both sexes therefore Heteroaima Sarsi agrees 

 with the o-enus Cumopsis, which is referred to the Bodotriidce, and it appears to differ from 

 that o-enus mainlv in the form of the third maxillipeds, which have the basis and merus 

 produced externally into pointed lobes and the carpus expanded internally. The species now 

 described agrees with Heteroaima Sarsi in having, in the male sex, the last two legs without 



