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Show 336 MR. F. E. BEDDARD ON THE ISOPODA COLLECTED [May 20, furnished with a median, backwardly projecting spine; these spines are considerably larger in the female than they are in the male ; the rest of the body is perfectly smooth and free from tubercles. I he epimera are shoVt and closely approximated, the points only ot the fourth, fifth, and sixth projecting freely; the suture separating the fifth thoracic segment from the first abdominal is continuous irom one side of the body to the other; the dorsal portion of the sixth segment is not represented as in the other Australian forms. Ine cephalic shield is almost triangular in outline from the great development of the ocular prominences and the posterior spine. The caudal shield is hexagonal in outline, the posterior end markedly bifid ; it has a longitudinal keel, and on either side, just below and to the inside of the notch which covers the articulation of the last pair of appendages, is a minute flattened tubercle, the abdominal segments have a median ventral spine, larger in the female. The second pair of antennae are slightly longer than the first pair; the fifth joint is remarkably large and swollen, and this feature serves to identify the species. The lower surface of the labium and basal portion of the mandibles and maxillipedes is m u c h sculptured. Station 163A, 35 fathoms; and Station 162, 38-40 fathoms. 8. SEROLIS LONGICAUDATA, n. sp. The aspect of this species is peculiar and very unlike the typical form of the genus. The anterior portion of the body is almost completely circular, and the caudal shield is extraordinarily long, about half as long as the rest of the body ; the epimera are short and truncate at their outer ends. The segments gradually increase in breadth up to the fourth ; the fifth and sixth are considerably shorter. The suture between the epimera and the tergal portion of segments two and three is situated about halfway between the articulation of the limb and the outer margin of the segment, and in the succeeding segments comes to approximate more closely to the point at which the limbs arise ; hence the epimera themselves gradually increase in length from the first to the sixth as in all other species, though the circular form of the body makes it appear at first sight as if the third pair were the longest. The single specimen contained in the 'Challenger' collection is a female; it measures 7 millim. in length and 5 millim. in greatest breadth. The surface of the body is quite smooth and free from tubercles; the sides of the thorax slope gradually downwards from the central portion, which is roof-shaped; the cephalic shield is not completely separated from the thoracic segment, the suture being incomplete posteriorly for a short space on either side of the median line; the fifth and sixth thoracic and the first abdominal segments are fused in the middle line. The caudal shield is pentagonal in shape and longitudinally carinate; the last pair of appendages are attached about halfway down the side of the shield, and from this point a faint transverse ridge passes across at right angles to the longitudinal keel; a curved ridge follows |