[ 3° 6 ] 
into little waves or wrinkles. In the little cavities of 
thefe I obferved fundry fmall feed-like particles, per- 
haps the fpawn of the animal : when magnified, they 
appeared of a fpherical form, a little compreffed. 
To the centre of the bafe, where the clutter of 
polypes unite, and make one body, there grows a four- 
square bony ttem of fix feet long, having four grooves, 
one on each fide. At the joining to the flefhy part, 
the bony ttem is very fmall, and a little twitted like 
the turn of a fcrew, extending a membrane like a 
bladder, for about two or three inches in length, and 
near an inch in breadth, from the flefhy part down* 
wards. The membrane then begins to clofe infenfibly, 
and becomes a cuticular covering to the bony ttem, 
which now increafes gradually, till it becomes a quar- 
ter of an inch fquare. Within five or fix inches of the 
bottom of the ttem the bony part begins to grow 
fmaller, till it comes to a point ; and the cuticular 
part becomes cartilaginous, and fupplies this tapering 
part with a quantity of this elaftic fubftance, equal to 
the deficiency of the bone. 
The ufe of this membrane, or bladder-like, fkin at 
the top of the ttem, may poflibly be intended to give 
the animal a power to raife and fall itfelf in the water 
at pleafure. 
It appears from the twift in one part of the ttem, 
that the ttem, when very fmall, and not fo bony, 
had met with fome violence, that had turned it out of 
its direction ; the mark of which has ftill grown on 
with it : for the ttem of the other fpecimen, taken at 
the fame time, was quite even. 
Upon cutting it acrofs, we difcover the diftindl 
lamince to each angle, riling from a fmall point in 
the centre, and feparated by a crofs, that joins the 
oppofite 
