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sentative inter se. From which we are driven to con- 

 clude ; first, that this quondam continent was densely 

 stocked at the beginning with foci of radiation created 

 expressly for itself* ; and, secondly, that the areas which 

 these various creatures had overspread, before the land 

 of passage was broken up, was extremely limited, or, 

 which amounts to the same thing, that their migratory 

 progress was unusually slow. 



Touching the two-fold question, of the local engage- 

 ment of this Atlantic district with specific centres of 

 diffusion, and the extreme slowness of their diffusive pro- 

 gress, much instruction may be derived from a contem- 

 plation of the conchological statistics. Porto Santo, for 

 instance, is a very small island (not more than seven 

 miles in length), yet the number of endemic species 

 which it includes is so perfectly astounding that it may 

 be appropriately termed a generic area of radiation. 



* It would seem, when viewed on a broad scale, as if particular 

 districts throughout the world had been made as it were the special 

 fields for the exercise of the creative force, or that, generic areas 

 of radiation were part of the elementary design. Thus, Professor 

 E. Forbes records his belief that most, if not indeed all, of the ter- 

 restrial animals and plants now inhabiting Britain are members of 

 specific centres beyond its bounds, they having migrated to it over 

 a continuous land, before, during, or after the glacial epoch. Hence, 

 since the greater number of them are supposed to have come from 

 the central Germanic plains, we may assume that those plains were 

 one of the primary areas of diffusion for a large mass of created 

 beings. There is good cause for suspecting that the Pyrenean 

 region may have been another ; and certainly all evidence would 

 tend to prove that this vast Atlantic province was, also, well stocked 

 with aboriginal forms. 



