Colour—various, greater part of body usually tinged with red but sometimes with blue, integument thick and more or less opaque. Length about ¼ inch. Hab. Lyttelton Harbour. On seaweed, usually at roots of Macrocystis. This species is very peculiar in appearance and presents several points of interest. The maxillipedes are shown in Pl. II., fig. 2 d. Both the basos and ischios bear plates, that of the former ending in two rounded teeth, that of the latter rounded at the end and with its inner edge setose, the meros has its distal portion produced externally in a rounded lobe past the extremity of the carpus, the propodos has its distal and inner margins setose, the setæ on the inner margin being minutely serrate; the dactylos is broad, subtriangular, and nearly free from setæ. The peculiar chelate character of the second pair of gnathopoda of male appears to be acquired only in fully-developed individuals; in smaller specimens they are subchelate, with the palm transverse, as shown in fig. 2g; intermediate forms between this and the fully-developed form shown in fig. 2f are also found. At first sight the carpus appears to be absent; I believe that it is joined on to the propodos, but the evidence of this is not quite satisfactory. The sixth segment of the pleon appears to be absent, unless the part that I have described as the basal portion of the last pair of pleopoda represents the sixth segment itself; if this be the case, the last pleopod will be represented only by a single rounded joint; in either case it certainly bears the appearance of being rudimentary and useless. Genus Montaguana. (Montagua, Spence Bate, Cat. Amphip. Crust. Brit. Mus., p. 54.) As the name Montagua was long ago used by Fleming for a genus of Nudibranch Mollusca, I have altered the name of Mr. Spence Bate's genus to Montaguana. Generic characters:—“The superior antennæ are as long as the inferior, and not furnished with a secondary appendage. The mandibles are not furnished with an appendage. The maxillipedes are pediform, unguiculate, and without, or with only rudimentary, squamiform plates. The first pair of gnathopoda are small, subchelate, the coxæ not developed into a squamiform plate. The second pair of gnathopoda are larger than the first, and have the coxæ very large, squamiform, deeper than the body, and produced anteriorly, so as to cover the organs of the mouth; the propodos is developed upon the same type as in the first pair. The pereiopoda are subequal; the coxæ of the two anterior pairs are very largely developed,