Trans. A'. Y. Ac. Sci. 48 7'^«- '4, 



are at the present day. The facts, which I have observed in my 

 study of fossil plants, compel me to reject any system of evolution as 

 an explanation of the observed diversity in leaf-forms. 



January 14, 1884. 

 Section of Geology. 

 The President, J- S. Newberry, in the Chair. 

 Thirty-two persons were present. 



The resignation of Dr. I. I. Higgins, as Resident Member, was 

 accepted, and Dr. Louis M. Cheesman, of Trinity College, 

 Hartford, Conn., was elected a Corresponding Member. 



A paper was read by Mr. B. B. Chamberlin, illustrated by a 

 series of specimens, on 



FIELD WORK IN LOCAL MINERALOGY. 



As our city extends its boundaries, the levelling of rocky elevations, 

 the opening of avenues and railways, and the construction of sewers, 

 afford continued opportunities for the local collector to pursue his 

 investigations and enlarge his store of trophies in this interesting 

 branch of natural history. 



The region beyond the Harlem River will now receive more atten- 

 tion than hitherto. 



Some of the more noticeable results of the writer's visits to various 

 localities in and about our city, during the past two years, may be 

 stated as follows : 



RipidoUte. — This variety of chlorite is abundant at the. dolomyte 

 beds in the vicinity of Morrisania, especially at 145th Street and St. 

 Ann's Avenue. 



It is concentrated near the surface of the dolomyte, in layers vary- 

 ing in thickness from a half inch to perhaps five inches. The color is 

 generally of a dull blue, and occasionally of an olive green. The 

 body of the deposit is a mass of folia or scales, usually not over 

 half an inch in diameter. The dolomyte immediately adjacent to the 

 deposits of ripidolite is mostly of a friable character and darkish in 

 color, varying from a dull violet to brown. 



A new locality for a local mineralogist which has lately attracted 

 my attention is the marble quarry on Jerome Avenue. Here the de- 

 posit of the above-named mineral is exhibited in a striking manner. 

 The layers are at times greatly distorted. 



Aggregations of the folia occasionally approach crystalline forms — 

 perhaps quite as near as the tender nature of the mineral will allow 



