Genus Teraticum, novum.

Body small. Eyes two. Coxæ of first four segments as deep as their respective segments. Antennæ with short flagella; upper antenna with a small secondary appendage. Mandible with an appendage. First gnathopod larger than the second, subchelate; second slender, chelate. Posterior pair of pleopoda uniramous. Telson single, undivided.

I have been obliged to make a new genus for the reception of the following species. In some respects it appears to resemble Kroyera, Spence Bate; but it is very distinct in others:—

Teraticum typicum, sp. nov. Pl. xviii., fig. 1, a to g.

Antennæ subequal, first joint of upper antenna equal in length to the second, but stouter; third about half as long as the second; flagellum of about four joints, only slightly longer than the second joint of peduncle; appendage very small and slender, of one long slender joint followed by a very small short one. Peduncle of lower antenna with the second last joint considerably longer than the last; flagellum not so long as last joint of peduncle. Peduncles of both antennæ quite free from setæ; flagella with a few short setæ. First gnathopod large, carpus triangular, nearly as broad at distal end as the propodos, propodos subquadrangular with an oblique row of short setæ near the centre of posterior margin, palm transverse, the part near the base of dactylos crenated, hollowed in centre with a small rounded projection in the centre of hollow; dactylos strong, curved. Second gnathopod slender, ischios long and slender, rather more than four times as long as broad; meros short; carpus about two-thirds as long as ischios, subtriangular; propodos considerably longer than carpus, subrect-angular, produced into a fixed finger against which the dactylos impinges; dactylos as long as fixed finger, and about one-third the length of the whole propodos. First two pair of pereiopoda subequal, last three increasing in size posteriorly, basa broad, that of fifth pair having the posterior margin serrate, meros produced distally and posteriorly; setæ on pereiopoda few and short.

Fourth pleopod with rami longer than peduncle, inner slightly larger than the outer, falciform; fifth with peduncle longer than rami; sixth with peduncle short, the single ramus as broad as peduncle at first, but narrowing distally. All the last three pairs of pleopoda without setæ. Telson triangular, end rounded, margin entire, a very small seta on each side near the end.

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Length about 1/12 inch.

Hab. Lyttelton Harbour. Three specimens only.

Of the three specimens which I have seen, two had the first gnathopoda as described and as drawn (pl. xviii., fig. 1, b and c); the third had the propodos projecting distally, so that the gnathopod might almost be called