1887.] NEW-YORK MICROSCOPICAL SOCIETY. 75 



Mr. Norris remarked the singular beauty of some of the newly 

 discovered diatoms. Those shown were from the Barbadoes 

 deposits, a locality which has yielded fine finds of foraminifera. 



Professor Henry G. Hanks read an interesting paper, illustra- 

 ted by diagrams, concerning a diamond found in this state. 

 The first diamond, he said, was found by Mr. Lyman, of New 

 England, who saw in 1850, in the new gold mines, a crystal 

 about the size of a small pea. It was slightly straw-colored and 

 had convex faces. From that time to the present these gems 

 have been occasionally found in our state, but never in large 

 numbers nor of unusual size. Professor Hanks said it has been 

 long his opinion that if hydraulic mining had been allowed to 

 continue a system of concentration would have been adopted 

 which would result in a larger production of gold and platinum 

 and in the finding of more diamonds. At the present time we 

 know of the existence of diamonds in five counties in the state, 

 as follows : Amador, Butte, El Dorado, Nevada and Trinity. 

 It is not unlikely that they may yet be found in California more 

 plentifully than before. 



A very beautiful and remarkable diamond has lately come 

 into the possession of J. Z. Davis, a member of the Microscopi- 

 cal Society, and this one Professor Hanks submitted for ex- 

 amination. It was found in 1882 at Volcano, Amador county, 

 by A. Schmitz. It weighs 0.361 grammes, or 5.570 grains, equal 

 to 1. 571 carats. It is a modified octahedron about three-tenths 

 of an inch in diameter, very nearly if not quite colorless, per- 

 fectly transparent, but not without some trifling inclusions and 

 faults. The form of the crystal is unusual. Professor Hanks 

 has not found such a one described or figured in books. The 

 general form as shown by examination is that of a regular octa- 

 hedron, but the faces seem convex. The whole crystal assumes 

 a somewhat spherical form and the edges of the pyramids are 

 channels instead of planes, but on closer examination it will be 

 seen that the channeled edges, the convex faces and the solid 

 angles are caused by an apparently secondary building up of the 

 faces of a perfect octahedron, and for the same reason the 

 girdle is not a perfect square, but has a somewhat circular form. 

 These observations were well shown by drawings showing in 

 enlarged form the outlines of the gem. The faces seem to be 

 composed of thin plates overlying each other, and each slightly 



