microscopic chambered shells. 117 
acea and of larger animals, minute examination 
sc OSes occasionally prodigious accumulations 
miscrocopic shells that surprise us no less by 
^ i^ndance than their extreme minuteness ; 
torrpHk” ^ '^h^ch they are sometimes crowded 
sll estimated from the fact that 
Soldam collected from less than an ounce and a 
Ttoanr::/:r^‘" Casdana, in 
TheresVofthe "^^^a^^^ered shells. 
of shel f of fragments 
shells, of minute spines of Echini, and of a 
sparry calcareous matter. > ^ m ot a 
Of several species of these shells, four or five 
hundred weigh but a single grain- of nn 
species he calculates that a fhous^nd bdivid^: 
to^r grain. (Saggio Orit- 
Or,rafico, 1780, pag. 103, Tab. III. fig. 22 H 1 1 
He further states that some idea of theii dimi 
r:: r. 
thronch . numbers of them pass 
nrirk^i ‘ paper m which holes have been 
pricked with a needle of the smallest size. 
rapidly ™°"M'ufwherwratti!rl*^ 
have°blTi, of microscopic shells 
deposits of sedimentary 
fieshwater formation. A strikino- 
CT 
