1^92.] On Biologic Regions and Tabulation Areas. 473 



framework, and another naturalist tabulates another order of Butter- 

 flies on a different geographic framework, the results of the two 

 naturalists can only be combined by doing the tabulation all over 

 again, instead of by a simple addition. 



Naturalists have not agreed on one system of primary reference 

 areas ; and, consequently, it is not possible to combine the results 

 attained by different writers. 



The first reason why naturalists have not accepted Wallace's 

 recommendation is that his regions do not appear the most natural 

 to many naturalists ; Professor Huxley, Dr. Giinther, and numerous 

 botanists have proposed widely different regkms as more natural. 

 A second reason why these regions have not been used for tabulations 

 is that their boundaries are (in many important cases) not accurately 

 denned. 



I have been for eighteen months past making trial of various 

 geographic frameworks on which to tabulate the distribution of 

 2000 species of plants ; and I have constructed a considerable 

 number of maps, and have executed trial tabulations of a few genera 

 on them. I have arrived at one conclusion which I deem of sufficient 

 importance to bring before this Society, viz., that the two objects 

 hitherto confounded in the designing of biDlogic regions must be kept 

 entirely separate. Biologic regions representing the natural distribu- 

 tion of Mammalia or of life are not convenient to use as tabulation 

 areas. I may venture to say, indeed, that the more perfectly natural 

 the biologic regions are, and the more complex and detailed their 

 boundary lines, the more impossible they are to use as reference 

 areas or as tabulation areas on any considerable scale. 



The idea of biologic regions presupposes a geographic framework 

 of some kind on which the area of each genus of animals or plants 

 was previously plotted. It appears to me that all naturalists, 

 zoologists, botanists, and paleontologists, might easily agree to use 

 one system of tabulation areas. Out of the results attained on this 

 system, they might construct various biologic regions, each to please 

 himself. 



I have constructed, as a reference map for my own tabulations, the 

 Map B. I would urge naturalists to use this, or that a committee be 

 appointed to design a better, which should be put out by authority. 



This Map B I have gradually arrived at by fixing down accurately 

 the boundaries, and otherwise modifying the Map A, which is 

 Wallace's map of zoologic regions. My object has been to make the 

 smallest alterations in Wallace's map consistent with easy tabula- 

 tion. 



The greater part of the paper here abstracted is occupied with a 

 detailed discussion of various boundary lines in the Map B, in order 

 to bring out clearly the principles which should guide us in forming 



