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Show 1885.] D U R I N G T H E V O Y A G E O F H.M.S. ' C H A L L E N G E R . ' 923 segments is a single median spine, one on either side of the median line on each of the three succeeding segments. The abdomen is oval in shape, with an immensely elongated telson spine twice the length of the abdomen itself. On either side are a pair of lateral spines, the posterior being placed dorsal to the articulation of the uropoda; from the ventral surface of the caudal shield behind the uropoda arises another spine, which is shorter in this species than in the next to be described. The uropoda are 5-jointed. Station 158, 1800 fathoms. 2. ACANTHOCOPE ACUTISPINA, n. sp. A single specimen, apparently a female, of this species was dredged off the west coast of Patagonia. The specimen measures 5 millim. in length. It has the same general form as the last species; but the three posterior thoracic segments, instead of being together double the preceding thoracic segments, are only equal in length to the second, third, and fourth of these segments. The upper surface of the body in this species has not the median spines described in Dolichurus spinicauda. The epimeral spines are of comparatively much greater length than in the last-described species, and they, as well as the general body-surface, are closely beset with short spines; these structures are also present in A. spinicauda, but apparently not to so large an extent. The abdomen has the same general form as in the last species ; but the terminal spine of the telson is much shorter, being only about equal in length to the abdomen. The two first appendages of the thorax are shorter as well as more slender than the succeeding. The uropoda are 3-joiuted. Station 302, 1450 fathoms. Geoyraphical and Bathymetrical Distribution. Although the Munnopsidae dredged by the ' Challenger' were in nearly every cases from very deep water, the genera of this family do range into shallow water considerably above the 300-fathom line, which is supposed with reason to represent approximately the boundary line between the abyssal and shallow waters. Nearly all the species described by Sars are from comparatively shallow water, though several descend into water of 300 to 500 fathoms in depth, e. g. Eurycope gigantea, 525 fathoms. In the southern hemisphere only one species has been found to inhabit shallow water. A Mun-nopsid was obtained on the shores of Kerguelen, which are so productive in other Isopoda, notably in the genus Serolis; this is a species of the genus llyarachna which I have not at present determined with certainty. The majority of the deep-sea species were obtained in the vicinity of land, for example, near to N e w Zealand and to the coast of South America. In many instances stations situated at vast distances from any land (such as Stations 157 and 158 between Australia and |