62 



considered asbelonging to Mantellia ; but should the more 

 compact part of the fossil, or its porous surface, display the 

 dwellings and evident labours of polypes, no doubt should 

 be entertained of placing it among the species of alcyonium. 

 This may be instanced, as has been just mentioned, in those 

 fossils which bear the forms of fruit : in sponge, is sp. fici- 

 formis; in syphonia, a correspondent form frequently occurs ; 

 in Mantellia, the fossil figured, Organic Remains, vol. ii. 

 PI. 11, fig. 3, may be instanced; and in alcyonium, is both 

 A.faus and A. cydbnium. 



Although M. Lamouroux has not thought proper to 

 reject from the preceding table several bodies which have 

 been considered as alcyonia, he is himself of opinion, that 

 the number should be much diminished : considering those 

 only as alcyonia which are evidently the production, and 

 have been the habitation of polypes. He accounts for 

 Lamarck having intermingled and confounded these animals, 

 by his having too frequently judged of them from the dry 

 specimens; but is of opinion that they may be readily 

 distinguished either in their living or dead state. 



In the recent alcyonia, the polypes or their cells may 

 be always seen on taking them out of the sea ; but nothing 

 similar is discoverable in sponges. In the alcyonia not only 

 is that pulsatory motion observable which is attributed to 

 sponge, but, in those alcyons which are ramified, the 

 branches are sometimes seen to be curved and afterwards 

 straightened again. This is particularly observable in 

 A. lobatum. The difference between the two animals is 

 also apparent on the examination of the dried specimens. 

 On a section, either transverse or vertical, being made of 

 dried sponge, no difference of substance is discoverable ; 

 from the centre to the circumference is the same organi- 

 zation : but on making a section in any direction through 

 the centre of the dried alcyonium, a structure more or less 

 fibrous, and a substance more or less grooved, will be seen 



