Microdentopus maculatus, G. M. Thomson (Ann. & Mag. N.H., ser. v., vol. iv., p. 331).

This species was described by Mr. Thomson, from a single specimen, a female. It appears to be moderately common amongst seaweed in the rock-pools at Lyttelton. Amongst some specimens answering very well to his description I took one which also agreed with that description in every particular except as regards the gnathopoda. These (plate VIII., fig. 3) are very peculiar, the meros is produced inferiorly into a long acute spine reaching slightly beyond the extremity of the succeeding joint, the carpus; this spine bears a small tuft of setæ about one-third of its length from its extremity. The carpus is large, and is rather more than twice as long as broad. The propodos is much smaller; its inner edge is fringed with numerous setæ. The last joint forms a strong finger slightly curved at the end, its inner edge is smooth; numerous long setæ arise at its base. The second pair of gnathopoda are of more normal shape, the meros not being produced into a spine.

The first pair of gnathopoda closely resemble those of Aora gracilis and Aora typica,^* though slightly different from both of them. Mr. Thomson has taken Aora typica in Dunedin Harbour, and he speaks^† of its resemblance to Microdentopus maculatus, and hints that they may possibly be male and female of the same species. The animal I have, though distinct