On the Pelagic Fauna of our Shores. 137 Genus Peltastes, Agass., 1838, amended. Syn. Hyposalema, Desor. Subgenus GoNiOPiiORUS, Agass., 1838. Genus Salenia, Gray, 1 835, amended. Subgenus Heterosalenia, Cott., 1861. XVI. — On the Pelagic Fauna of our Shores in its Relation to the Nourishment of the Young Food-Fishes. By Prof. M'iNTOSH, M.D., LL.D., F.R.S., &c.* By the term pelagic fauna is meant the inhabitants of the whole body of the water from the surface to the bottom. This immense area, it is well known, varies greatly in depth, viz. from 4655 fathoms (that is upwards of five miles), as sounded by the American exploring-ship ' Tuscarora,' near the Kurile Islands in the North-east Pacific, to a few inches, as on gently sloping saiuly beaches. The pelagic fauna of the surface of the ocean has for ages attracted the attention both of voyagers and of scientific men. In the tropical and subtropical regions especially the abun-dance and variety of such animals are remarkable ; yet they are not confined to these warmer areas, certain types, as copepods and pteropods, occurring in such countless multitudes in the arctic seas that they form the food of the right whales. The colder waters, just mentioned, however, do not, as a rule, present the brightly coloured and conspicuous swimmers of the warmer areas, such as Portugaese Men-of-war, Venus's Girdles, the exquisite siphonophores, pelagic annelids (e. g. Alciojxi), and certain types of pteropods and crustaceans. In our own seas, even the most superficial observer on the eastern coast must have been struck by the great beauty and abundance of the lilac Aurelice, the deep purple of the young or the rich brown of the adult Oyanece, frequently stranded in multitudes on sandy beaches in autumn ; while in the milder waters off the western shores the greater variety of the purple and reddish medusas (e. g. Pelagia^ j3iquorea, Modeeria, Oceania), the occasional occurrence of such truly oceanic forms as Phi/salia, Velella, and lanthina, the long chains of Salpte, and the crystalline calices and orange polypites of * Abstract of Introductory Lecture to the Class of Natural History, University of St. Andrews, November 1-3, 1886.
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