4 
PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Another gratifying result of going over the ground with these 
geologists was the offer of further cooperation. Professor Crosby’s 
work is necessarily mainly areal and structural, and although he 
has himself paid for a number of chemical analyses and has received 
additional assistance from several of his students, it was very de¬ 
sirable that this should be supplemented, especially for the igneous 
rocks, by microscopic and chemical work. Dr. White of Columbia 
has very kindly done considerable microscopical work on the Blue 
Hills rocks, and Dr. A. *S. Eakle of Harvard has kindly supple¬ 
mented this by investigations of the plutonic rocks, especially on 
chemical lines. The intricate nature of the problem of the geology 
of this region has been the cause of the successive delays in com¬ 
pleting the work, and it would still have remained unfinished if 
Professor Crosby had not this year given an extraordinary amount 
of time to this purpose. 
The manuscript of Part 3, “ The Blue Hills complex,” is now in 
the hands of the Secretary, 375 pages, with 8 plates and 26 figures. 
Two chapters which Mr. Grabau is writing, one on the fossils and 
one on Lake Bouv5, an extinct glacial lake, noticed in the report 
for 1895-96, are in the hands of the author, but are stated to be 
practically finished. An important accession of new fossils lately 
received, including the Sears collections from Nahant and Mr. 
W. W. Dodge’s collections from Braintree, has prevented the com¬ 
pletion of the descriptions of the fossils in time for this report, but 
it is gratifying to notice that these accessions have about tripled 
the materials for investigation. 
The work on the Neponset Valley, Part 4, of the Boston Basin 
work, has been actively pressed. Outside the areal and structural 
work done by Professor Crosby, Dr. Florence Bascom, of Brvn 
Mawr college, accepted an invitation to contribute by studying the 
volcanic rocks, and Mr. F. C. Ohm of the IT. S. geological survey 
has also kindly taken the work on the thin sections, while Professor 
Crosby has arranged for a sufficient number of chemical analyses 
to supplement Miss Bascom’s investigations. 
Professor Crosby ends his report to the Curator as follows : “ The 
willingness of other geologists to cooperate with me is a great 
encouragement and leads me to hope that the ideal end of this work 
may be realized ; viz : an illustrated handbook of the local geology of 
our own neighborhood accompanied by a complete collection on 
exhibition in suitable rooms. This should not only be creditable to 
