The Asiatic Fishes of: the Family Anabantidne.

To sum up shortly the result of this induction.It seems fairly proved that Mya arenaria, one of the very commonest shells in the present seas of Scandinavia, Britain, and Belgium, where the conditions are singularly favourable for it, has only recently invaded those shores.Secondly, that it is not an Arctic shell as has been supposed, but a boreal one.It has not been found living in Arctic waters, and its alleged occurrence there has been due to a mistaken inference.Hence, all deductions as to glacial climate deduced from its having occurred in certain beds must fall to the ground.It may well be, as Brogger suggests, that when it recently invaded the European seas it came from North America.On the other hand, the same shell existed abundantly in Britain in the times of the Middle and Later Crag, and has been found in Scandinavia at Uddevalla, affording some evidence that a portion at all events of the Uddevalla shell-beds are what is called preglacial or late Crag.So that the mollusc must have died out for a considerable time or been exterminated.Meanwhile it becomes a very good test to discriminate between the shells of the Crag and those derived from it, on the one hand, and the subsequent fauna of the raised beaches etc., down to recent times, on the other.The cause of its extinction and the explanation of its reintroduction, unless the latter was due to hviman agency, are equally puzzling.The notion that Mya arenaria was the victim of that Deus ex macMna, the Ice KgQ^ is excluded by the fact that the companions of this shell in our modern estuaries suffered no such extinction, but survived all through the period from the Crag age until our own day.2. The Asiatic Fishes o£ the Family Anahantidae.