126 ROCHESTER ACADEMY OF SCIENCE. [Jan. 12, 
Mr. Howell also described a fault which he had observed in 
Stony-brook Glen, in which the overhanging wall had risen, an illus- 
tration of the abnormal form. 
Mr. J. M. Davison described a phenomenon at Saratoga, where 
the Trenton limestone was so mixed with fragments of the underlying 
calciferous sandrock as to give it the appearance of a breccia. 
Oct. 21, 1890. The evening was mostly spent in discussion as to 
whether the specimens of rock from Stony-brook Glen, exhibited at 
the Section, June 3d, were boulders or concretions, but without arriv- 
ing at definite conclusions. 
Professor Fairchild exhibited two forms of clinomoter, and ex- 
plained their use. 
Mr. Preston exhibited a specimen of Dadmanites aspectens, the 
property of Professor Arey, found at LeRoy, N. Y., which was the 
only complete specimen of this trilobite known, although heads and 
tails of this species have been found separately in abundance. 
Various specimens were presented for identification. 
Nov. 4, 1890. The topic for the evening was Cleavage. Professor 
Fairchild exhibited several specimens, illustrating different kinds of 
cleavage. 
Noy. 18, 1890. The officers of the Section for the ensuing year 
were elected as follows: Chairman, Mr. E. E. Howell; Vice-Chair- 
man, Mr. S..G. Crump; Secretary, Mr. H: LL. Preston; Sectional 
Committee, Mr. J. M. Davison and Rev. John Walton. 
Dr. Franz Muecke exhibited a specimen of bog iron ore and 
manganese: from Brighton, near Rochester. Also an incrustation of 
leaves and twigs from the travertine bed, of Mumford, N. Y. Mr. W. 
W. Gilbert exhibited a specimen of silicified wood from the drift in the 
Genesee Ravine; also zelenite from Frost Avenue. 
Professor Fairchild described the mineralogical character of the 
Niagara limestone in Pike’s quarry on Frost Avenue. 
Mr. Worthington exhibited fossil coral from England. 
The topic for the evening, Concretionary Structure, was discussed 
by various members, and Professor Fairchild exhibited numerous 
specimens illustrating various forms of concretionary structure. 
Mr. Walton exhibited a fine concretion, showing a fossil as a 
nucleus. 
Mr. Davison showed a thin section of silicified oolite, from Center 
county, Pa. 
