53 



through tlie spongeous part ; the siliceous impregnation 

 having solidified this part, and left the tubules unfilled. 



It is not to be doubted that, when the specific dis- 

 tinctions of the several specimens belonging to this genus 

 have been ascertained, the number of its species will be 

 found to be very considerable*. 



At PL 1, fig. 8, is represented a transverse section of 

 one of the stems of a tulip-formed specimen, in which the 

 bundle of tubules are shown ; and at fig. 7, the superior 

 extremity of the same fossil is given, with the numerous 

 terminations of the tubuli. These may be also generally 

 discovered on the sides of the depression or cavity which 

 sometimes exists in the superior termination. 



The existence of these animals appears to have been 

 confined to that sea from whose waters the green sand for- 

 mation was deposited ; no traces of their remains being 

 mentioned as found in the strata of any of the preceding 

 or subsequent formations. 



Animalisation has, in this genus, proceeded a degree be- 

 yond that in which it exists in sponge ; since, added to the 

 spongeous texture, is the bundle of tubes which has been 

 here considered as yielding its generic distinction. 



* From the account given by Miss Benett to the Geological 

 Society, respecting these fossils, it appears, that they are found in 

 the Valley or Common of Warminster, in the reddish yellow sand, 

 at a depth seldom exceeding two feet, on the sides of the hills. At 

 Whitburn, near Claythill, in the same neighbourhood, the green 

 sand comes to the surface, and these fossils are found in it. At 

 Boreham, on the east side of Warminster, the grey sand is upper- 

 most, and there, but most rarely, are found fossils of the same 

 kind. ''These fossils," it is observed by Miss Benett, " appear to 

 belong to the top of the sand formation, without regard to the sort 

 of sand. The yellow sand appears to be the grand depot of them : 

 in the green sand, large specimens predominate ; but those of the 

 grey sand are in a higher state of preservation." These fossils 

 were discovered by Mr. George Warren, of Warminster, to whom 

 Miss Benett states herself to be indebted for them. 



