456 



THE GEOLOGIST. 



certain old sea-beds which are scattered at intervals over some of the western 

 departments of Trance, extending inland along the valley of the Loire, as far 

 eastward as beyond Blois, to be met with in some of its branches northwards 

 — an old arm of the Atlantic, with dimensions nearly equal to those of our 

 English Channel, long since laid dry. These old sea-i3eds are the ' Taluns of 

 Tom-aine.' " 



Lower down to the south, from the Island of Oleron across to the Adour, 

 was another great indent of the Atlantic — an eastern extension of the Bay of 

 Biscay. Over this once depressed area there are sea-beds which contain an 

 assemblage like that of the Toui-aine deposits, the Fakms Jaunes of Grateloup." 



He further regards the fauna of the Atlantic as primarily composed of a 

 northern and a southern element, and " It is to be remarked," he says, " that 

 the northern constituents of our present Atlantic fauna are not met with in the 

 older fauna of the Taluns, nor in the equivalent assemblages further south. 

 Northern forms had not, at that time, extended into that part of the Atlantic 

 which lies west and south of the British Islands. Their gi'cat migration south- 

 wards took place subsequently to those great physical changes which converted 

 into dry land those portions of western Erance above referred to, and which changes 

 were trifling in amount when compared with those of the same date in other 

 parts of the Atlantic, and within the Mediterranean area. The physical change 

 which liberated the northern fauna has been indicated on independent consi- 

 derations. It has been shown that there is good evidence of the former conti- 

 nuity of a coast-line from the north of Greenland to the north of Lapland, and 

 that, consequently^ the Atlantic did not then communicate with the Arctic 

 basin ; it was only when this barrier was removed that a free passage south 

 was opened out to Arctic forms." 



With the exception of a limitation at its northern extremity, "the Atlantic 

 is an old area of depression. There was an Atlantic Ocean for the nummuKtic, 

 cretaceous, and palaeozoic periods, during each of which it had its distinct 



representative forms on its opposite sides." 



With other equally interesting topics and reflections, the remaining chapters 

 conclude a book which, from its intrinsic value and moderate price, will doubt- 

 less meet with an extensive sale, and prove a usefid foundation as well as an 

 encouragement to further investigations by naturalists of the interesting sub- 

 ject to which it is devoted. 



Dura Den : A Monograph of the Yellow Sandsto7ie, and its remarkable Fossil 

 Remains. By John Anderson, D.D., E.G.S., E.P.S., &c. Edinburgh: 

 Thomas Constable and Co. London : Hamilton, Adams and Co., 1859. 

 Eifeshire, the general contour of which, in its gentle and undulating outlines, 

 partakes more of the aspect of the English downs than of the bolder and more 

 rugged features of the Scottish mountain-tracts, forms the eastern portion of 

 the great central coal-district of Scotland. The Ochils, a chain of trap-hiUs 

 varying in the extent of their range from four hundred feet in height to nearly 

 three thousand in Bencleugh and Dalmyatt, traverse its northern boundary, 

 and with the short but elevated table-land of the Lomonds rmniing through 

 t]ie_ central portion, separate the county into three well-defined subordinate 

 regions corresponding to tln-ee equally-marked geological distinctions. Erom 

 the Loinond-heights the view is spoken of as charming. " Overlooking the 

 w liolc county, and the two noble rivers by which it is encompassed, with the 

 (in,ii;m Ocean to the East, the town of Stirling and the 'lofty Ben Lomond' 

 I o the west, the rugged serrated .outline of the Grampians to the north, and 



zones of distribution 



correspouding provinces of 



