—— 
es) 2 = e ss 
Microscopic Organisms in Hornstone. 385. 
Arr. XXXIX.—Discovery of Microscopic Organisms in the Sili- 
ceous Nodules of the Paleozoic Rocks of New York. * 
_At Prof. Dana’s suggestion, Dr. M. C. White, well known for 
his deyotion to the microscope, has examined various specimens 
of the hornstone nodules found in the Devonian and Silurian 
tocks of this country, with a view to determine the presence of 
" Organisms analogous to those well known, to exist in the flints of 
the Chalk. This research has been rewarded by the discovery 
of abundant organisms referable to the Desmitliex, besides a few 
Diatomacese, numerous spicula of sponges, and also fragments of 
the dental apparatus of Gasteropods. Among the Desmids, there 
8 a large ee of forms of Xanthidia supposed to be the S 
ids, besides an occasional duplicated Desmid ; slat 
The hornstone nodules from the Black River limestone (as 
Well as the Corniferous) have been since examined also by Mr. 
F. H. Bradley with similar results. 
our plan 
e analogy of these hornstone nodules to the flints of the 
Chalk is obvious; and the discoveries here announced may be 
The extreme abundance of the bornstone nodules in our'pa- 
tion to the labors of the microscopist. It will be remembered 
by those who undertake such examinations that the use of tur- 
Pentine renders the chips of chert almost as transparent as glass. 
We add a note from Dr. White with figures of some of the 
more frequently recurring forms hitherto observed by him.— Es. 
= als ee ‘ i ining the mitroisapse structure 
gaged in exami 
of Mitanited hes tebeunts Does I send you ie accompanying sketches of 
MS ge — which I have discovered. They ame of spicules al ge . 
es of sponge and fragments of sponges, Desmidiex, severa ] 
Xanthidia, i eee y Diatoms. Horn- 
