356 J. W. Bailey on Fossil Diatomacee. 
is not established on good physical evidence; (4.) all species 
which however abundant in the lower series disappear in the u 
per—either altogether, or ascend into it through so very limited 
a space above the line of demarcation as to produce no general 
impress on the upper fauna;—when all this has been done, I 
have no doubt that the number of common species will fall con- 
siderably below ten per cent: perhaps as low as the percentage 
shown by the Paleozoic series of North America or Bohemia; 
but not so low as the per centage shown by the Cambrian and 
Silurian rocks of the north of England. 
Arr. XXXV.—New method of disintegrating masses of Fossil 
Diatomacee ; by Prof. J. W. Bainey. 
any masses of fossil Diatomaceze are so strongly coherent, 
that they cannot be diffused in water, (for the purpose of mount- 
ing in balsam,) without a degree of mechanical violence which 
reduces to fragments many of the most beautiful and interesting 
forms. This is particularly the case with some specimens from the 
“infusorial deposits” of California. Some of these I endeavored to 
break up, by boiling in water and in acids, and also by repeated 
freezing and thawing when moistened, but without good results 
in either case. At last it occurred to me that the adherence might 
be due to a slight portion of a siliceous cement which the cau- 
tious use of an alkaline solution might remove without destroy- 
ing any but the most minute shells of the Diatoms. As the case 
appeared a desperate one, a ‘‘ heroic remedy” was applied, which 
was to boil small lumps of the diatomaceous mass in a strong 
solution of caustic potassa or soda. This proved to be perfectly 
efficacious, as the masses under this treatment rapidly split up 
along the planes of lamination, and then crumbled to mud, which 
being immediately poured into a large quantity of water ceased 
to be acted upon by the alkali, and gave when choteaaiey 
washed, not only all the large shells of the Diatoms in a state 0 
unhoped for perfection, but also furnished abundance of the ml- 
nute forms. Having obtained by this method highly satisfactory 
results from specimens from many localities I can confidently 
recommend it as an addition to our modes of research. 
The following directions will enable any one to apply the pro- 
cess. Put small lumps of the mass to be examined into a test tube, 
with enough of a solution of caustic potassa or soda to cover 
em; then boil over a spirit lamp for a few seconds, or a few 
minutes, as the case may require. If the solution is sufficiently 
strong, the masses will rapidly crumble to mud, which must be 
P at once into a large quantity of water, which after subst- 
