148 PROCEEDINGS OF THE BOSTON MEETING 



phrase, are the petrographical poles toward which differentiation tends. The 

 existence of regions of incomplete petrographical specialization, which are 

 sometimes considered to be evidence against the truth of the conception of the 

 tectonic control of the primary differentiation of the original (possibly basal- 

 tic) magma into the secondary magmas of special petrographical provinces, 

 appears to the writer to be, on the contrary, a necessary product of such 

 primary differentiation. 



In the present paper, however, the writer has not laid the stress on this 

 conclusion as to general petrogenesis and the major acts of differentiation 

 such as appears in this abstract, but in the absence of an intensive study of 

 the occurrence of the granites and alkaline syenites, etcetera, he has refrained 

 from discussing at length such conclusions as are here indicated, though the 

 evidence of the basic intrusive rocks, which alone has been studied in detail, 

 appears to point in this direction. The bulk of the paper is given up to a 

 review, country by country, throughout the world, of the occurrence of basic 

 and ultrabasic rocks, as it appears in the literature available, and it is offered 

 with the hope that it may serve, w^hen associated with the detailed study of 

 the conditions during the development of other types of rocks, in forwarding 

 the knowledge of petrogenesis, which has been so advanced by the illuminating 

 generalizations put forward during the last thirty years. 



Presented by title in the absence of the author. 



MICHIGAN METEOR OF NOVEMBER 26, 1919 

 BY WILLIAM HERBERT HOBBS 



Presented by title in the absence of the anthor. 



ANNUAL DINNER 



The evening of Tuesday, December 30, was devoted to the annual sub- 

 scription dinner of the Geological Society of America and the Paleonto- 

 logical Society and their guests, in which there were 156 participants. 

 President John C. Merriam acted as toastmaster, and addresses were 

 made by Messrs. I. C. White, Frank D. Adams, D. W. Johnson, James F. 

 Kemp, A. H. Brooks, ♦E. A. Daly, John M. Clarke, Lawrence Martin, 

 G. D. Louderback, and H. S. Washington. 



Session of Wednesday Morning, December 31 



The Society, meeting in Joint session with the Paleontological Society, 

 was called to order at 9.20 o'clock a. m. by President John C. Merriam. 

 The Secretary informed the body that the Council, having learned of 

 the financial straits in which the Geological Magazine of England found 



