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and Sponges, the void places $ in coral and lithophy- 
tons, the cortical parts. 
hach of thefe animals, according to their kind, 
furnidi fubdances, differing, as much in confid- 
ence as in form. That of coral is extremely hard, 
and compact 3 the madrepora and millepora are of 
a ftony, but more loofe texture j the coralline 
is dill more foft j the lithophyton of a fubdance 
nearer horn than done ; and the fponge is foft and 
eladic. 
We obferve a great variety in the operations of 
nature : the crab, the cuttle-fifh, and the fea fpider, 
are endow’d with a tedaceous covering 5 the efculent 
fea polype, and others of that clafs, have no fuch 
defence. So mod of the animals, hitherto taken 
notice of in this treatife, have a fecure retreat ; but 
there is a production, denominated by Imperatus 
Lonca marina , which has no fuch convenience. It 
is, if I may be allow'd the expreffion, a foft madre- 
pora. It grows at the bottom of the fea, and is a 
feries of circular tubes, of about half an inch long, 
and of two or three lines in diameter. Each of 
thefe, at the end mod remote from the centre, is fur- 
n idl’d with a fphinCter, from which are occasionally 
protruded the legs or claws of the animal, like thofe 
before-mention’d. The tubes themfelves are like- 
wife at pleafure lengthen’d and Shorten’d. They 
are faden’d to the rocks by a common broad furface, 
after the manner of coral, and fuch-like marine pro- 
ductions, and are of a coriaceous fubdance. Hither 
likewife may be referr’d the foft lithophyton, ufually 
call’d the fea mulberry, and defcribed by our author, 
N n n which, 
