J Sy Geology and Paleontology. j 843 
which relate solely and exclusively to one thing? (Perhaps Mr. 
Gilbert would call them monotaxic. r is it not rather a cam- 
; 5 
it would seem, from certain parts of the address, that Mr. 
= exhausted. He says, in regard to the acceptance by the 
~engress of a classification of the eruptive rocks, — 
“With the 
Temodelled rapid growth of knowledge and ideas, classifications are continually 
and Sapo the best is in danger of becoming obsolete before it has been printed 
Sratigraphic stes d every group is local. . . . If I have properly characterized 
Classification , if they are both natural and local, it goes without saying that 
sible.» "Of the str ozen or so systems... iS 
SSible, ata of all countries in a | 
We ; t d a i "~ 
remark tht ay ing “if” not there one would be tempted to 
