Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/367

354 dentata, Rhodomela cristata and lycopodioides, and Fucus Mackaii in like manner characterize a northern flora on the coasts of Scotland and of the north of England and Ireland.

The fauna of our seas, like the flora, presents distinct northern and southern relations. These are especially manifest among the Invertebrate animals, and also among the fishes. The few marine Mammalia included in the British list, are mostly derived from northern regions though some, as Phoca vitulina and Delphinus phocæna are constant and characteristic residents. Phoca barbata and Delphinus melas may be regarded as representatives of a Boreal type and Trichechus rosmarus, Delphinus albicans, Monodon monoceros, Balæna mysticetus and Balænoptera boops and rostrata as arctic forms, wandering to the limits of their range. Some of the larger Cetacea appear to have been more frequent visitors to our shores anciently—even during historical times—than now. The marine Reptilia represented by Sphargis coriacea and Chelonia imbricata are members of a southern type, and visitants from an opposite direction to that whence we have obtained our aquatic mammals.

The distribution of our native marine fishes exhibits distinctly four types, of which two, a northern and a southern, belong to great ichthyological provinces, the bounds of which approach, but can scarcely be said to meet in our seas—and two, a British and an oceanic, the former including those species either peculiar to or chiefly developed in the British Seas, and of which the Irish Sea may be regarded as the centre or capital, and the latter of pelagic forms occasionally or frequently visiting our shores in common with most of the coasti of the north Atlantic.

The occasional visitants of the south-western coasts of England indicate that the southernmost parts of our islands are not far from the northern bounds of the great province of south-European fishes, a region of which the coasts of the Peninsula may be regarded as the centre, and the Mediterranean as in a great measure an extension eastwards. To this province belong many of our rarities, such as Serranus cabrilla, Serranus gigas, Mullus barbatus, Pagrus vulgaris, Pagellus erythrina, Dentex vulgaris, Labrus iulus, Muræna helena and Ophidion imbarbe.