Page:Transactions NZ Institute Volume 15.djvu/124

Idoteidæ and approaches the Tanaidæ. The legs consist of an anterior series of four, and a posterior series of three, and this, according to the figures given by Bate and Westwood, appears to be the case with the Tanaidæ. This peculiarity is also possessed by the Amphipoda to which Phreatoicus has a considerable superficial resemblance due chiefly to the flattened form of the body, best seen in the abdomen, and to the fact that the segments of the pleon have the integument produced downwards, but also to the Amphipodan facies of the legs and the last pair of pleopoda.

The precise place of Phreatoicus in any system of classification cannot as yet be indicated with certainty, but one thing is made clear by the discussion, viz., that Phreatoicus, possessing as it does affinities to several distinct groups, must be of very considerable antiquity.

The occurrence of this species has been somewhat remarkable. Ever since January, 1881, I have collected or had collected for me all the Crustacea that were observed to come up; nothing new was found until the beginning of September, 1882, when a single specimen of Phreatoicus was obtained, and in the short time since then six other specimens have been found.