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Show 924 ON ISOPODA COLLECTED B Y T H E ' CHALLENGER.' [Dec. 1, Kerguelen in the southern hemisphere, and Station 252 in the middle of the North Pacific) yielded examples of the family. The distribution of this family over the floor of the ocean appears to be much wider than that of any other family of the Isopoda. While the genera Serolis, Arcturus, and others, of which the ' Challenger obtained specimens from the deep sea, were almost invariably obtained in the immediate vicinity of land, this was by no means invariably the case with the Munnopsidae. The frequent occurrence of more than a single species at the same station appears to show that this family is largely represented in the abyssal fauna. At Station 146, for example, three distinct species were obtained, viz. Eurycope sarsii, E. fragilis, and Munnopsis australis. The wide range of certain species is of importance. Eurycope fragilis ranges from Borneo in the north to near Kerguelen, and close to the antarctic ice-barrier in the south. Acanthocope spinicauda from Station 158 is represented off the west coast of Patagonia by Acanthocope acutispina, which only differs slightly from it. The greatest depth which any Munnopsid is known to inhabit is 2175 fathoms ; a single specimen of Eurycope abyssicola was dredged from this depth at Station 68 in the Atlantic. In my Report on the genus Serolis 1 pointed out that in Serolis Bromleyana and 8. antarctica, which have a comparatively wide range, the individuals from the more southern localities are considerably larger than those that inhabit the more northern latitudes. This is strikingly shown in the case of Eurycope fragilis. The more southern forms of this species are considerably larger than the northern forms. Nearly all the species of Munnopsidae described by Sars and others are of comparatively puny dimensions, the largest being Eurycope gigantea, which attains the length of 33 millim. In striking contrast are many of the specimens obtained from deep water both in the northern and southern hemispheres by the ' Challenger ;' as instances, may be mentioned Eurycope pellucida, which measures nearly 2 inches in length, and E. fragilis, which measures 1| inch. In this group, as in so many others which are represented both in deep and shallow water, the deep-sea species attain to the largest size. Several of the new species described in the present paper are remarkable. Eurycope spinosa is unique by reason of the great development of spines upon the dorsal surface of the body ; this character has not been met with in other Munnopsidae, which have at most a covering of slender hairs, or a few spines, as in Eurycope atlantica. The development of spines upon the body is a character met with in other deep-sea Crustacea, though its meaning is not clear. Another very remarkable species is the one which I have named Eurycope pellucida. As its name implies, it is transparent, the integument being thin and but little calcified ; the condition of the specimen might naturally suggest that it had just changed its skin, if a well-developed colony of Hydroids upon some of the segments |
