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Madiepora Corals, than to any known fpecies of" 
the genus of Animals called Pennatula. At the 
fame time I allow his remark to be very juft, where 
he obferves that the Hydra Arttica or Great Green- 
land Polype, which I have defcribed in the Philofo- 
phical 1 ranfadtions, and in my Effay on Corallines, 
is certainly a fpecies of Pennatula ; but he will 
find, from both the drawing and defcription, which 
I have given of it, that it is not ftxt by its bafe, but 
floats freely about in the fea ; whereas this Alcy- 
onium as well as his (which differs in colour from 
ours) are always found fixt by their bafe to fome 
folid fubmarine body, and confequently cannot be 
admitted among the Pennatula?. 
I muft now conclude this letter with a fhort ac- 
countof a new difcovered fpeciesof Pennatula, which 
my ingenious friend John Greg Eiq; of Charles 
Town in South -Carolina, difcovered on that coaft 
andprefented to me fome time ago. This beautiful 
purple animal is of a compreffed kidney fhape. 
The body is about an inch long, and half an inch 
acrofs the narroweft part, it has a fmall roundifti 
tail of an inch long proceeding from the middle of 
the body, its tail is full of rings from one end to the 
other like an Earth-Worm, and along the middle 
of the upper and under part of it there is a fmall 
groove which runs from one end to the other. 
I examined carefully the point of the tail and 
could find no perforation in it, which is agree- 
able to what I have obferved in the reft of this 
genus. 
The upper part of the body is convex and near a 
quarter of an inch thick ; the whole furface of it is 
covered over with minute yellow ftarry openings, 
through 
