REVIEWS. 



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temperate tides that lave our ovra favoured shores cherish, a submarine popula 

 tion intermediate in character between both." Thus, chiefly by the laboiu-s of 

 Torbes, the Eiu'opean sea-area has been divided into six zoological provinces, 

 within which he considered there were to be reckoned as many distinct centres 

 of creation. The first and northernmost being the Ai'ctic^ extending tlu'ongh- 

 out that portion of the European seas within the Arctic Cncle. The second, 

 the Boreal " including the seas which wash the shores of Nor^'ay, Iceland, the 

 Faroe, and the Zetland Isles. The tliird, tlie Celtic, "in wliich rank the British 

 seas, the Baltic, and the shores of the continent from Bohuslan to the Bay of 

 Biscay." The foui'th, the Lusitanian, includes the Atlantic coasts of the Pen- 

 insula. The fifth, the Mediierranean, includes also the Black-sea ; and lastly, 

 the Caspian, a region now completely isolated from all the others. AH these 

 provinces are succinctly but perfectly, as far as existing knowledge goes, con- 

 sidered in their geographical, physical, and geological relations, and the 

 characteristic life-forms of each carefully made out. Of these it was suggested, 

 however, by Forbes that the Mediterranean and its dependencies may possibly 

 be a chain of offsets from the Lusitanian area ; wliile Mr. Austen seems to con- 

 sider the Boreal fauna as a modificfition of the Ai'ctic. In the chapter on the 

 geographical distribution of sliells in Mr. Woodward's " Manual of Mollusca," 

 the lists of shells occurring in the several marine regions are tabulated, and these 

 lists will be found to be useful companions to this " History of the Eiu'opean 

 Seas." In the ninth chapter " On the Distribution of Marine Animals," 

 amongst other interesting topics, that of those " outliers," or remarkable 

 assemblages at spots, often far distant from the present boundaries of a pro- 

 vince, of animals of its characteristic species, is treated very forcibly in 

 its geological aspect. Such assemblages, for example, often occur witliin 

 our own. Celtic province, and are so peculiar and so isolated that tliey can not 

 be accounted for by any facts coimected with the present disposition of cur- 

 rents, or other transporting influences. They are " usually located in a hole 

 or valley of considerable depth, from eighty to beyond one hundred fathoms, 

 and consist of species of molluscs of a more northern character than those of 

 the zone or province in which they occur." 



"The explanation which Edward Forbes gives of these ' outliers' is as 

 follows : — When the bed of the sea of that period, when in cur latitudes the 

 fauna was more northern than it is now, was upheaved, the whole was not 

 raised into dry land, but tracts of greater depth, and which consequently were 

 tenanted by peculiar forms, still remained under water, though under diiferent 

 depths. In these changes a portion of a fauna would be destroyed, but such 

 species as could endui-e alterations in vertical range would live on." 



Of such outliers, or isolated groups of fossil remains, Mr. Austen quotes the 

 remarkable instance, noticed by M. Barrande, of a patch in one of the lower 

 divisions of the great Palaeozoic series of Bohemia, of as many as sixty species 

 of forms not agreeing with those characterizing the horizon in which they occur. 

 These forms are surmoimted by beds containing the characteristic species of 

 the same lower division, but the sixty species thus isolated appear again as a 

 component part of the fauna of the "upper division" of the same palcTozoic 

 series. Such isolated assemblages are regarded hj Mr. Austen as true outHers, 

 and " vrill serve to suggest curious and interesting geological inferences in the 

 earlier history (both natural and pliysical) of the pjiropean area." 



Of the antiquity of the fauna of the Eu;' ^, Mr. Austen writes: 



"The fauna of the Eiu'opean seas dates ba-;.. - ^iii or first a})j)earance to 

 times which, on the scale of the geologist, follo\\ next after the Nummulitic 

 period (Eocene). So far as Earop!-,;.:ii seas are concerned, they do not contain 

 a single species in common with the [oliu- of the nummiditic group. The 

 earliest reeords of the occupation of the Aclcintic by any existing forms are 



