1887. | NEW YORK ACADEMY OF SCIENCES. 57 
forms a bed running from 54th street and Tenth avenue to 60th 
street and the Hudson River, where it goes under the water. In 
parts it is a mass of fibres radiating from centres, but elsewhere 
it becomes serpentine or tale. The fibrous portion has been 
called hydrous anthophyllite by Dr. Torrey, and classed with the 
amphibole group by Dana,! and pronounced to be the result of 
the alteration of an asbestiform tremolite. Analyses are given 
in the Annals Lyc. Nat. Hist., VIII., 123, and in Dana’s Min., 
p. 242. The bed sometimes becomes a blackish serpentine with 
calcite distributed, forming ophiolite. I have been unable to 
find an outcrop of the bed, as it has been built over and covered 
up, although stray pieces and boulders are to be found along the 
river. 
The preserved descriptions indicate it to have run throughout 
its length close beside a granite vein. It is recorded also that 
boulders of the anthophyllite were formerly distributed very 
generally over the island, and in Mt. Vernon it has been col- 
lected by Mr. Fowler. One is inclined to conjecture, not with- 
out reason, yet with no positive proof, that the deposit must have 
been more extensive than is outlined above, and have been 
eroded away, or that all of its localities have not been recorded 
as yet. 
Epidote.—In the region about Fourth avenue and 101st street, 
epidote occurs in deposits of considerable size, forming a rock. 
It isa granular, sandy mass in parts, interstratified with horn- 
blende in thin layers, and in other parts of a very firm compact 
character. The fissures are lined with a coating of crystals, 
which are small but of considerable brilliancy. I have seen it 
elsewhere as a mineral in fissures, but here it is abundant enough 
to be called a rock, possibly what is called by Dana, epidosyte. * 
Limestone.—The northeast corner of the island consists of 
limestone, known as ‘‘ Kingsbridge Marble,” and it outcrops 
elsewhere further south, but in small quantities. It is firm and 
massive, and in all stages of decomposition down to calcareous 
sand. ‘The massive sometimes weathers into a saccharoidal form 
before it crumbles to sand. The color of the limestone is a dirty 
white. It has been employed as a building stone for one or two 
large dwellings on the Kingsbridge Road, but is not well adapted 
for such a purpose, as it 1s weak and falls an easy prey to the 
weather. I have seen statements that it is dolomitic,*® but find- 
ing no analyses, I have analyzed it myself. ‘wo specimens from 
1 Dana’s System Mineralogy (1877), p. 242. 
2 ** Man. Min. and Lith.,” p. 453. 
’ Cozzens, p. 15, siates that he obtained 28% MgCOs. 
