£± FOSSIL ALCYONIA. 



Farther dff- But here is not the whole of the difficulty : several of the 



theilpo^s- f° ssil9 ' w h»ch will be presently described, possess some of 



ing other cha^ the characters of acidia and actinia, with those of the 



SfStTn/frtm s P on S e or ah-yoninm; thereby rendering their distinct and 



all known correct classification almoft hopeless. Hence, although I 



s P ccies * shall in general speak of these bodies as alcyonia ; 1 am 



aware, that when their histories have been" elucidated by 



the inspection of more illuftrative specimens, several of them 



may claim other designations. 



The consideration of another circumftance leads to the 

 necessity of giving up every idea of distinguishing the alcy- 

 onia from the sponges, whilst in a mineralized state. Among 

 the fossil zoophytes which claim a situation under one or: 

 other of these genera, by far the greater number are such 

 as are so totally different from any known species of either 

 alcyonium or sponge, as to render it almost impossible to 

 determine under which genus they ought to be placed. 

 Under these circumstances, you must perceive that the at- 

 tempt to separate these fossils, by specific distinctions, at 

 present, would be hopeless: it can only be effected when, 

 by additional observations, their nature and forms are more 

 perfectly known. 



When it is recollected what very considerable variations 

 in form, are found to take place in the recent individuals, of 

 the several species into which these subftances are divided ; 

 and when it is considered, that whilst passing into a mine- 

 ralized state, their figure and appearance may be also much 

 changed, it may be suspected that hardly any opportunity 

 of fair comparison could be found, between the recent and 

 fossil alcyonia. 

 Their change This however is very far from1>eing the case; and indeed 

 c^me^to" wnen we reflect on tne transmutation which has taken 

 stone, wonder- place ; that a soft, gelatinous, or spongy substance, has 

 fully httle. become a hard and ponderous stone, we cannot but be 

 affected with a high degree of astonishment ; especially on 

 perceiving, that this great and extraordinary change of 

 substance has been accompanied by so little change of form* 

 In consequence of this I trust I shall be able to place before 

 you many bodies, even in a silicified state, which will im- 

 mediately appear to have been animals of this description, 



belonging 



