116 



a degree of adhesion, that whilst the animal secured this vacuum, no 

 removal of it from that spot could take place, unless accompanied by 

 destruction of the parts of which it was composed. On the other 

 hand, whenever the animal was disposed to submit itself, with its 

 dwelling, to the direction of the waves, it would only be necessary tx> 

 contract the perpendicular fibres terminating on tiie edge of the infe- 

 rior surface, by which that edge would necessarily be raided ; and by 

 continuing this process through each successive circle towards the cen- 

 tre, the air would gain access to the vacuum, and the animal would 

 be immediately loosened. Whilst affixed by its inferior surface to any 

 other substance, the whole of its circumference would be formed into 

 as many fixed points as there are fibres proceeding up its superior 

 surface. These fibres, thus fixed at their inferior part, and terminating 

 in the sides of the longitudinal cavity on the upper part, would, by 

 their contraction, draw downwards the whole alcyonic mass, and at 

 the same time widen the central longitudinal opening, by which ac- 

 tion the contents of the ventricular cavity must have necessarily been 

 expelled. The relaxation of these fibres would of course be accom- 

 panied by the refilling of the cavity, and by the alternate contraction 

 and relaxation of these fibres, the alternate filling and emptying of the 

 ventricular cavity. 



The probability that the animal possessed this power of thus form- 

 ing a vacuum, and of fixing itself, like the remora, or sucking-fish, is 

 rendered exceedingly probable, by both the specimens which I pos- 

 sess, as has been already observed, having on their inferior surface 

 concavities, not only differing in their magnitude, but also in their 

 form, arising from different circles of the series having been more or 

 less acted upon, by which corresponding risings and depressions have 

 been left. From the rarity of the fossils, I was not disposed to insti- 

 tute any examination of them which should, either chemically or me- 

 chanically injure their surface. 



