270 ORTMANN — DISTRIBUTION OF DECAPODS [Aprils, 



animals, we tnust pronounce it impossible to create any scheme what- 

 ever that covers all cases. 



3. Under these circumstances it is incorrect to regard the creation 

 of a scheme of animal distribution as an important feature or purpose 

 of zoogeographical research. 



Thus we are justified in saying that zoogeographical study, as 

 introduced by Wallace, is not directed in the proper channels, and 

 we are confronted with the question, If the creation of regions of 

 animal distribution is not a matter of first importance, which is the 

 vital point in this branch of research ? 



This question has been practically answered by many writers. I 

 name the following: G. Pfeffer, E. von Ihering, H. A. Pilsbry, 

 R. F. Scharff, C. Hedley, W. Kobelt, H. F. Osborn, A. Jacobi 

 (besides others), and these we may take as representatives of the 

 modern tendency in Zoogeography. According to these authors 

 the chief aim of zoogeographical study consists — as in any other 

 branch of biology — in the demonstration of its geological develop- 

 ment. We have to designate this most emphatically, as the final 

 goal of Zoogeography : the retracing of the present animal distri- 

 bution to its beginning in the past, and a corollary of this is the 

 reconstruction of the ancient physical features of the earth's surface, 

 since these in the first place have guided the development. In the 

 latter respect the distribution of land and water in past times is all- 

 important and the easiest to be traced. 



Thus Zoogeography becomes a very important aid not only to 

 physical Geography itself, but also to historic Geology. 



The above introductory remarks seem necessary, because the 

 purpose and methods of the new tendency in Zoogeography have 

 been frequently misunderstood, and especially because it was not 

 seen that in this way the fruitless discussions on the limits and 

 value of the different zoogeographical regions, etc., have been ren- 

 dered unnecessary. Yet it is a habit among zoogeographers to 

 create or discuss zoogeographical regions according to Wallace's 

 ideas, and this is done not only by writers who, like Wallace and 

 Sclater, are principally opposed to any progress in Zoogeography, 

 but also by those who are familiar with the new ideas about the geo- 

 logical development of animal distribution. The old method has 

 become an integral part of this branch of science to such a degree 



