EDWARD FORBES 29 



that area and have migrated to it over continuous land. 



" (5) The Alpine floras of Europe and Asia are fragments 

 of a flora which was diffused from the North. The deep sea 

 fauna is in like manner a fragment of the general glacial 

 fauna. 



" (6) The termination of the glacial epoch in Europe was 

 marked by a recession of the Arctic fauna and flora north- 

 wards, and of a fauna and flora of the Mediterranean type 

 southwards, and in the interspace thus produced there 

 appeared on land the general Germanic fauna and flora, and 

 in the sea that fauna which is termed Celtic. 



" (7) All the changes before, during, and after the glacial 

 epoch appear to have been gradual and not sudden, so that 

 no marked line of demarcation can be drawn between the 

 creatures inhabiting the same element and the same locality 

 during two proximate periods." 



I have omitted some of his conclusions which can no 

 longer be regarded as based on fact : others require some 

 modification. Much has been found out during the last 

 eighty years, and it is not surprising if some of Forbes's 

 brilliant and far-reaching speculations have proved incorrect 

 or incomplete. For example, the three southern sub-floras 

 of Forbes, in place of being the oldest as he supposed, we now 

 know must have been the most recent ; and it is now very 

 doubtful to what extent they migrated over continental land 

 now submerged, as he supjDOsed, or were carried by birds, 

 currents, or other natural agencies. 



But while admitting some such imperfections due to the 

 scanty knowledge of that day,^ we must recognize that this 

 was a notable contribution to the theory of distribution, far 

 in advance of anything known at the time. It practically 

 opened up a fresh fleld of investigation, and proved to be the 

 starting-point and stimulus of much subsequent research. 

 About 1850 Forbes prepared his remarkable map of dis- 

 tribution of marine life over the oceans of the world, and 

 of homoiozoic belts, which was probably the first attempt 



