1885.] NEW YORK ACADEMY OF SCIENCES. 77 



Six stout crystals form the axes of the structure, across which 

 are symmetrically arranged more slender crystals at angles of G0°. 



Tlie color of the crystals, after the removal of the outer crust 

 by an acid, is blood-red. 



The associated minerals are chlorite, in radiated globes, al- 

 bite, oligoclase, and scapolite. A handsome Brown Spar and a 

 zeolite, thought to be Harrin(jto)iite, have also been noticed; 

 also two or three small but highly-modified crystals of a light- 

 jellow Sphene. 



Farther up the avenue appears that peculiar variety of chlo- 

 rite known as Jefferisite, Interesting specimens are those where 

 the Jefferisite appears as a coating to trilateral or wedge-shaped 

 fragments of quartz. I have thought these singular forms due 

 to cavities in crystallized albite from which they have been 

 removed. 



In Morningside Park may be found a broad vein of pure milky 

 4^uartz, much of which is laminated — a somewhat unusual form 

 of this mineral. 



On Washington Heights, near High Bridge, laminated quartz 

 terminates in splintering masses of loosely-aggregated grains, re- 

 minding one of icicles, or finials to a Grothic tower. The quartz 

 occasionally presents highly polished surfaces produced by glacial 

 action. 



Along the east bank of the Harlem River may be noticed frag- 

 ments of Bog-iron ore, much of which is highly iridescent. This 

 is on Dana's list of Harlem minerals. 



In conclusion, reference may be made to the mineralogical 

 ■character of the ridge directly east of the Harlem River. 



The formation is a regularly laminated gneiss furnishing ex- 

 cellent building material, sometimes of much beauty due to its 

 distinct shades. It is noted for the absence of the potash feldspar, 

 its place being supplied by a whitish variety, probably albitic. 

 Further than this, the formation is devoid of special interest to 

 the mineralogist. Nor do the excavations along the line of the 

 new aqueduct for a number of miles furnish material worthy of 

 an extended notice. 



President Newberry exhibited and commented upon three 

 interesting pamphlets which he had recently received. They 

 are (1) "On Luminiferous Ether," by Professor De Volsen 

 "Wood, of the Stevens Institute ; (2) " On the Denudation of 

 the two Americas," by T. Mellard Reade, of Liverpool; (3) ''On 

 the Geological Age of the North Atlantic Ocean," by Professor 

 Edward Hull, Director of the Geological Survey of Ireland. 



The first paper gives an interesting summary of what is known 



