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on the first : in general their branches appear directed 
towards the main sea. 
The larger Polypidoms are rarely found in places 
exposed to violent currents, or the full shock of the 
waves. It is in the hollow of rocks, in the submarine 
grottos, in the shelter of large and solid masses, and 
above all, in those gulfs where the waters are not 
agitated, that these singular beings fix themselves. 
Many of them appear formed to share the powerful 
action of the surges ; their pliant branches bending to 
the movements of the waters, and balancing the ani- 
mals that form them in the agitated medium. Others 
again, constructing immovable and rocky dwellings, 
give them the form of tunnels, placing themselves in 
the interior : while some, by their re-union or aggre- 
gation, form an extended mass, narrow in proportion 
to its length, prolonging it uninterruptedly many ter- 
restrial degrees, and forming an immovable dike, which 
usually crosses the great currents of the ocean, whilst 
its solidity and greatness are continually augmenting. 
Sometimes these madrepore rocks curve in the form 
of a circle ; the polypi that inhabit it, established in 
its interior, elevate by slow degrees their rocky dwell- 
ings to the surface of the waters : thus, ever sheltered 
in their labours, they load by slow degrees the bottom 
of the deep ; but in the higher part of this impenetrable 
