on a new Marine AnhnaL ^4j 



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 increaiing 

 its canal, being only compofed of foft parts. This, however, 

 is no argument againfl: its doing it, for every fhell fifh has the 

 power of removing a part of its fliell, fo as to adapt the new 

 and the old together ; which is not done by any mechanical 

 power, but by abforptlon. 



The tribe of animals which have tentacula confids of an 

 almoll: 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 moil 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 Pembrokeihlre, 

 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 (hell is wanting. 



Since I began this Poftfcript, I find there is a defcrlption of 

 a double-coned Terebella, publiflied by the rev. Mr. Cor di- 

 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 ere£led they fpread from the cone as from a 

 center. This proves that the double-coned tentacula alfo have 

 different fpecies. 



Vol. LXXV. Z z s x p l a- 



