6 PHILOSOPHICAL TRANSACTIONS. [aNNO 1785. 



same time \vith the animal, and grows and increases with it : and if we consider 

 all tiie circumstances, this last would appear to be most probable, and agree best 

 with the different phenomena ; for the coral is lined with a shell, which could 

 not be the case if the animal was continually increasing this hole, both in length 

 and breadth, in proportion to its growth ; but if the coral and the animal in- 

 crease together, it is then similar to the growth of all shells, whether bivalve or 

 univalve. The animal does not appear to have the power of increasing its 

 canal, being only composed of soft parts. This however is no argument against 

 its doing it, for every shell fish has the power of removing a part of its shell, so 

 as to adapt the new and the old together ; which is not done by any mechanical 

 power, but by absorption. The tribe of animals which have tentacula consists 

 of an almost infinite variety, and many of the species have been described. 

 Of that kind however which has the double cones, he believes hitherto no ac- 

 count has been given. It is most probably to be found in the seas surrounding 

 the different islands in the West Indies ; for he once received an animal from St. 

 Vincent's ; which, on examination, proved to be the same animal with that above 

 described, only that the moveable shell was wanting. 



After writing this postscript, Mr. H. found a description of a double-coned 

 Terebella, published by the Rev. Mr. Cordiner, at Bamf in Scotland, which 

 was found on that coast ; in which the cones have their tentacula passing 

 out from the end, and when erected they spread from the cone as from a 

 centre. . This proves that the double-coned tentacula also have different 

 species. 



Explanation of the Figures. — Fig. 1 , pi. 1 , is a drawing of the animal after death, as it appeared 

 in spirits, a, the under side of tlie body ; bb, the cartilages which attach the animal to the sides 

 of the cavity in which it lies ; c, one of the cones covered by its membrane in a collapsed state ; 

 t>, the lowest spiral turn of the membrane and its tentacula spread out ; ee, tlie cut edges of the 

 divided membrane, which are turned on each side to show the cone ; f, the cone as it appears in 

 the intervals between the spiral turns of the membrane ; o, the moveable shell, with the smooth 

 cartilaginous covering, in an outside view ; h, the flattened end of the moveable shell, with hair on 

 it J II, the two claws tliat arise from the surface of the flattened end of the moveable shell } k, the 

 anus, into which a hog's bristle is introduced. 



Fig. 2 is a drawing of the animal, with its tentacula expanded in search of food, as it appears in 

 the sea ; taken from a sketch made in Barbadoes, where no draughtsman could be procured while 

 the animal was alive : a, the sort of brain-stone in which the animal was discovered ; h, the exter- 

 nal prominent shell ; cc, the membrane which is protruded with the cones and moveable shell, and 

 makes a fold over the edges of the prominent shell ; dd, the membranes and tentacula in a state of 

 expansion ; e, the inner side of the moveable shell, as it appears when protruded ; f, the hole in the 

 brain-stone as it appears when the prominent shell is broken off, and which may be seen in many- 

 specimens of brain-stone. 



