63 



passing from the centre to the circumference ; and on the 

 surface will be found a distinct skin or bark-like covering, 

 with numerous foramina, some of which are hardly per- 

 ceptible. These foramina appear to be the openings of the 

 radiating fibres, or tubes rather, and in some species are 

 very evident. 



To endeavour to trace the fossil remains of alcyonia to 

 the strata in which they were originally infixed, has hitherto 

 been accompanied with but little success : this has been 

 partly owing to the incorrect accounts which have been 

 given, respecting these and similar substances, by the 

 earlier writers on fossils ; and partly to the difficulty of 

 discovering these fossils when imbedded in stone, in the 

 more obvious characters of which they are likely to parti- 

 cipate, and thereby become more difficult of detection. 



The fructiform figures which the spongeoid fossils so 

 frequently possess, had obtained for them, to a late period, 

 the names of those fruits which it was thought they most 

 nearly resembled : and even when, in a former work, the 

 present writer removed these substances from the vegetable 

 kingdom, he was still unable to discover in them such 

 characters as would allow him to decide which specimen 

 should be considered as sponge, and which as alcyonium. 

 It is a remarkable circumstance, and not easy of expla- 

 nation, that, after numerous eager examinations with pow- 

 erful glasses, he has never seen, to his knowledge, the 

 characteristic radiating or decussating fibres of the internal 

 part of the alcyonium. In the fossils represented, Organic 

 Remains, vol. ii. PL 11, fig. 4 and 8, where the appearance 

 of a cortical substance led to the belief that these substances 

 are of alcyonic structure, and although the specimen, fig. 4, 

 in particular, possesses such a degree of transparency as 

 allows the discovery of organic structure, in that part 

 which is connected with its cortical covering, no appearance 

 of fibres can be discovered. 



