88 GENESIS OF THE AKIETID^. 



merits to the north, to which Waagen adds Dorsetshire and Wiltshire in southern 

 England. VI. North English Basin, from Gloucestershire to Yorkshire inclusive. 

 VII. North German Basin, including Hanover, Brunswick, and the neighbor- 

 hood of Magdeburg. 



We have not needed to use these divisions precisely as laid down by Waagen, 

 but it is interesting to remark that they accord more or less completely with the 

 observations on the faunas here recorded. Our principal interest has been, of 

 course, in the central portion of each basin, and not in the more deficient records 

 of outlying localities. The South German basin is as it has been given by 

 Waagen. His Helvetic basin appears to be a natural division, with the exception 

 of the departments of Saone et Loire, the Cote d'Or, and the Rhone. The Cote 

 d'Or has appeared to us to be the centre of a different basin, which extended in- 

 definitely through the departments to the westward, and also to the south until 

 it met the fauna in the valley of the Rhone described by Dumortier. Whether 

 such closely contiguous faunas as that of this valley and the Cote d'Or ought to 

 be designated by distinct names we cannot pretend to decide, but that they differ 

 materially from the point of view of the evolution of their faunas seems to us 

 highly probable. 



The faunas of northeastern France and Luxemburg, though perhaps in a dis- 

 tinct basin from those of Westphalia, Hanover, etc., which are properly included 

 in the North German Basin, are all similar in so far as they contain similar resid- 

 ual faunas. The basin of the Rhone includes the departments mentioned as in 

 the Mediterranean basin by Waagen, with the exclusion of the southeastern part 

 of the department of Var, which, as shown by Dieulefait, belongs to the Italian 

 basin. We have not been able to study any collections from Wiltshire, but the 

 Dorsetshire fossils of the Lower Lias, though certainly presenting a very distinct 

 facies and association of forms from those of Waagen's North English basin, have 

 not seemed to require separation into a different basin. The fossils do not resem- 

 ble those of any other fauna so closely as the}' do that of the rocks in the rest 

 of England to the northeast, and, though it may be natural to make this separa- 

 tion, we have not required it for the immediate purposes of this memoir, and have 

 consequently spoken of the entire region as the English basin. 



The Lias in territories to the north, like Scotland and Sweden, is deficient in 

 Ammonitinse, and Judd 1 remarks upon the estuarine character of the deposits. 

 At Dompau and Doshult in northwestern Sweden a few poorly preserved fossils 

 show the presence of the bucklandian fauna. It is possible that these deposits 

 may have a yet undiscovered fauna of Ammonitina? distinct from more southern 

 localities ; but so far as one can see, the forms of the Swedish basin are not dis- 

 tinct from those of the faunas of North Germany. 



Neumayr has already traced in a general way the origin of the fauna of 

 Central Europe to the Mediterranean province, and we think a still further 

 advance has been made practicable by the methods of constructing genetic series 

 as advocated in this monograph, and the discovery of definable cycles in the 

 genesis of forms. Though our conclusions have been reached under the dis- 

 1 Quart. Journ Geo!. Soc. London, 1S70. XXIX. p. 9S. 



