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The obfervations, which I have made upon fome 
kinds of polype-beds, lead me to think, that what 
are called polypes, in thole bodies, which are ob- 
ferved to come out of and return into the cells, are 
more than the heads of the animal. I have feen 
fome, which had a bag, into which pafs’d their 
food, which I faw them fwallow ; and another bag, 
into which paded the grofieft part of that food, after 
it was digelled. This is the cafe, for inlfance, of the 
plumed polypes, which I defcribed at the end of the 
third memoir, in the work publilhed by me on one 
kind of frefh-water polypes. 
Monf. Donati has obferved divers very curious 
fads in the journey, which he made into the moun- 
tains. He has, in particular, traced out an immenfe 
bed of marine bodies. This bed croffes the higheft 
mountains, which feparate Provence from Piedmont, 
and lofes itfelf in the plains of Piedmont. 
He has likewife obferved a mafs of rock, which 
forms the extremity of a pretty high mountain, the 
foot of which is walked by the fea. This rock is, 
at a confiderable height, intirely pierced by pholades, 
that fpecies of marine fhell-fifh fo well known, which 
digs cells in the Hones. It appears from hence, that 
this rock was fome time covered by the fea. Ac- 
cording to Monf. Donati, the fea has infenfibly re- 
tired from the parts, which were walked by it ; 
and he thinks, that there muft have been a very 
confiderable fpace of time between that and the 
time, when this mountain, pierced by pholades, was 
covered by the waters of the fea. He deduces his 
opinion from the following fad. There is in this 
rock, pretty near the furface of the fea, a natural 
cavern 
