Page:The Zoologist, 4th series, vol 4 (1900).djvu/67

Rh connection between the Mediterranean and Japanese Seas are supported by Dr. Alcock, who considers that the "hypothesis that appears to offer the most satisfactory explanation is, that a very considerable part of the fish fauna of the Oriental region originated from, and to a certain extent is a remnant of, the fauna of the Tertiary Mediterranean of Prof. Suess—of a MediterrneanMediterranean [sic] that extended from the present Gulf of Mexico, through the present Mediterranean basin, far into the Eastern Hemisphere." Species whose distribution may be used as evidence for this hypothesis are not only pointed out among these fishes, but also have been detailed by Dr. Alcock among the deep-sea Madreporaria and Brachyura of the same region. If the number of Indian genera of marine fishes are estimated at three hundred and fifty, and of species at one thousand two hundred; "then over fifty-six per cent. of the genera and close on five per cent. of the species are also found in the Atlantic-Mediterranean region." The argument is much advanced and clearly elucidated by a large chart compiled from Plate 11 of Dr. E. Koken's 'Die Vorwelt und ihre Entwickelungsgeschichte,' showing the supposed coast-lines of the Tertiary continents and the then Great Inland Sea.

Rainbow Trout (Salmo irideus var. Shasta), whose natural home is the Pacific slope rivers, has been largely introduced into the waters of various portions of the world. It has succeeded wonderfully well in New Zealand, where specimens have been taken reaching nine pounds in weight; in this country one of the first authentic reports of its colonization was a capture in Warwickshire in 1892 from a lake stocked in 1890. But success in the introduction of this fish depends upon a proper knowledge of its life-history. "The natural zone of the Rainbow Trout may be roughly said to be from 35° to 45° N.—that is to say, the latitude of Spain and the South of France"; and the best developed form of the true S. irideus var. Shasta "has for its original environment water not liable to freeze, and situated in a country the mean temperature of which is not below 55° F., and