on a new Marine Animal 1 
breadth, in proportion to its growth ; but if the coral and the 
animal increafe together, it is then fimilar to the growth of all 
fhells, whether bivalve or univalve. 
The animal does not appear to have the power of increafing 
its canal, being only compofed of foft parts. This, however, 
is no argument again ft its doing it, for every fheii fifti has the- 
power of removing a part of its fhell, fo as to adapt the new 
and the old together ; which is not done by any mechanical 
power, but by abforption. 
The tribe of animals which have tentacula conlifls of an 
almoft infinite variety, and many of the fpecies have been de- 
fcribed. Of that kind, however, which has the double cones, I 
believe hitherto no account has been given. It is moft pro- 
bably to be found in the feas furrounding the different iflands 
in the Weft Indies ; for I received an animal, fome years ago, 
from Mr. Oliver, furgeon, at Tenby in Pembrokefhire, 
which he had procured from a gentleman at St. Vincent’s ; 
which, upon examination, proves to be the fame animal with 
that above defcribed, only that the moveable fhell is wanting. 
Since I began this Poftfcript, I find there is a defcription of 
a double-coned Terebella, publifhed by the rev. Mr. Cordi- 
ner, at Bamf in Scotland, which was found upon that coaft ; 
in which the cones have their tentacula palling out from the 
end, and when eredted they fpread from the cone as from a 
center. This proves that the double-coned tentacula alfo have 
different fpecies. 
Z z 
Vol. LXXV. 
EXPL A- 
