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Show 102 MR. F. E. BEDDARD ON ISOPODA COLLECTED [Feb. 2, seventh thoracic segment and the abdominal shield is a narrow free abdominal segment, which is ridged like the posterior segments of the thorax. The abdominal shield is almost circular in its outline anteriorly; posteriorly it terminates in a triangular-pointed extremity ; the posterior region is slightly serrated. Kerguelen, 120 fathoms. 2. PLEUROGONIUM SERRATUM, n. sp. This species, like the last, is represented by a single female example measuring 3 millim. in length. The head is small and almost enclosed by the following segment of the thorax ; the frontal margin is straighter than in the last species, and the articulation of the antennas is not so near to the posterior boundary of the head; the hinder margin of the semicircular notch which lodges the antennae is prolonged outwards into a longish pointed process, which extends laterally nearly as far as the epimeron of the first thoracic segment. The thoracic segments are so like the last species that no special description is needed. The most characteristic and obvious difference between the two species is in the abdominal shield, which has, however, the same general shape in P. serratum as in P. albidum; in the former species the lateral margin as far back as the articulation of the uropoda is strongly serrated ; there is no trace of any such serrations in P. albidum except along the posterior extremity of the caudal shield behind the uropoda, in which situation they are absent in P. serratum. Kerguelen, 120 fathoms. 3. PLEUROGONIUM MINUTUM, n. sp. The third new species of this genus is represented by a single female example, dredged off Tristan da Cunha. It measures about 1 millim. in length. The general shape of the body is like that of the other species. The epimera of the thoracic segments are not prolonged into spines as in the last two species, but are rounded in the four most anterior segments and truncated in the posterior thoracic segments. The abdominal shield is oval, tapering posteriorly ; anteriorly the margins of the abdominal shield are serrated, but the serrations are not nearly so marked, nor do they extend over so great an area as in P. serratum. In the two last species the antennae are twice the length of the antennules; in the present species they are longer, but only half as long again: in this respect therefore Pleurogonium minutum is more typical, that is to say it agrees more closely with the northern forms described by Sars. Off Tristan da Cunha, 100-150 fathoms. ACANTHOMUNNA, nov. gen. This genus is like Munna in outward form, and is furnished with a pair of eyes elevated on stalks as in that genus ; the thoracic limbs are entirely like those of Munna except that they terminate in a |
