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Show 1886.] DURING THE VOYAGE OF H.M.S. 'CHALLENGER.' 109 female there are several shorter ones in addition. The first abdominal segment has a single row of comparatively short backwardly-directed spines; on the second and third segments these spines get to be considerably longer, especially the lateral spine on either side, which marks the commencement of the abdominal shield. The abdominal shield in both sexes is covered with longish curved spines; just above and near to the termination of its lateral margins are an extremely long pair of spines directed outwards and slightly upwards. The proximal joints of the antennae and of the thoracic appendages are furnished with spines. The uropoda are tuberculate in the male and spiny in the female. Station 147 ; 1600 fathoms. 5. ARCTURUS PURPUREUS, n. sp. This species is represented by a single female, which is of a purplish colour. It measures 18 millim., the length of the antennae is 31 millim. On the head between the eyes are a pair of long forwardly curved spines; the hinder portion of the head is occupied by a rounded median convexity; on the antero-lateral margin is a very short forwardly directed spine, beneath which the margin is excavated by a semicircular notch. Of the first four thoracic segments, the fourth is rather the shortest; each of the segments bears an outwardly directed spine on each side of the body, corresponding in position to those upon the head; close to the lateral margin of each segment and projecting over the epimeron is another long spine ; the first segment differs from the succeeding in having no free epimera, and the lateral margin has two spines instead of one, of which the anterior is the longer; the fourth segment has also a second spine at its postero-lateral margin. Of the three posterior thoracic segments the first is the largest; the epimera of all have a long outwardly directed spine ; the first of these segments has in addition a tergal spine on either side exactly overlying the epimeral spine. The first abdominal segment has a pair of long lateral spines and a pair of short ventral spines ; the third segment has a pair of lateral spines. The abdominal shield is oval, with a faintly marked central keel, terminating posteriorly in a long spine; its lateral margins are flattened and unite posteriorly ; on either side are two flattened spines situated at equidistant intervals. The antennae and anterior thoracic limbs have a few spines upon the proximal joints; the uropoda are granulated, but bear no spines. Station 23 ; 450 fathoms. 6. ARCTURUS SPINIFRONS, n. sp. This species reaches to a length of 13 millim., the antennae measuring 20 millim. The body is extremely tuberculate, but there are no spines except a single pair upon the head ; the lateral margin of the head, as in A. anna, is notched ventrally. The four anterior thoracic segments are subequal, each has a posterior ridge which |