FOSSIL DIATOMACE. 93 
mous deposits of fossil diatomaceze that are found in some 
formations, I subjoin the observations of Dr. Bailey on an 
elegant fragile species, which hangs together in clusters, 
appearing like spiral chains, and is about ;', of a line in 
diameter ; it is named Meridion vernale. 
“ This fresh-water plant is seen in immense quantities in 
the mountain brooks around West Point, the bottoms of 
which are literally covered in the first warm days of spring 
with a ferruginous-coloured mucous matter, about a quarter 
of an inch thick, that, on examination by the microscope, 
proves to be filled with millions and millions of these ex- 
quisitely beautiful siliceous organisms. Every submerged 
stone, twig, and spear of grass, is enveloped by them ; and 
the waving plume-like appearance of a filamentous body 
covered in this manner, is often extremely elegant. Alcohol 
completely dissolves the endochrome (sofé colouring matter) 
of this species, and the frustules are left as colourless as 
glass, and resist the action of fire.” * 
The yellow or ochreous scum observable in ponds, ditches, 
and stagnant pools, is an aggregation of diatomaceze, whose 
frustules are ferruginous, and of such extreme minuteness, 
that a billion of their cases would not be more than a cubic 
inch in bulk.t 
Fossiz Diatomace®.—From this notice of a few recent 
types, we proceed to the investigation of the fossil remains 
of this tribe of Algee. 
In peat-bogs and swamps, both of modern and ancient 
date, masses of a white marly or siliceous paste (hydrate of 
silica), are often observed, and these are found upon micro- 
scopical observation to be wholly made up of the frustules 
of Navicule, Bacillarie, Galionelle, &c., with an inter- 
mixture of the needle-like spicules of fresh-water sponges. 
Many of the peat-bogs of Ireland contain layers of a white 
* Trans. Amer. Assoc. Geolog. 1843, p. 152. + Ehrenberg. 
