71 



from the injuries which they have sustained, but little information can 

 be acquired respecting them. The characters by which this would 

 be determined are chiefly, the form of their ramifications, and the 

 form and disposition of the small stellular pores with which they are 

 beset. But the fracture of the branches, and the obliteration of the 

 pores, are among the most frequent injuries which these bodies have 

 sustained : hence the ascertaining of their species, a circumstance 

 particularly desirable, can but seldom be accomplished. 



The specimen figured at Plate VIII. Fig. 9> which is from Mr. 

 Sirange's Collection, and was obtained from France by that gentle- 

 man, is a madrepore imbedded in a very hard chalk. The fragment 

 is too small to allow any determination with respect to its species. 



The madrepore represented at Plate VIII. Fig. 6, is from the Col- 

 lection of the same gentleman, and appears to have been obtained, 

 with many other similar fragments, from Switzerland. The surface is 

 pretty thickly beset with cavities, shallowly, but rather extensively, 

 stellated. 



Of the millepores, at least from the few which I possess, or have 

 had the opportunity^ of seeing, I suspect, that not many are found in 

 a mineral state. 



The ramose mi lie pore, from Wiltshire, Plate VIII. Fig. 3, is in a 

 tolerable state of preservation : its pores are very distinctly seen by 

 the aid of a slight magnifier, as at Fig. 11. It is imbedded in a very 

 hard and close lime-stone of a brown colour. 



Of the genus CELLEPORA I am unable to speak decidedly. In the 

 masses of calcareous stone of St. Peter's Mount, at Maestricht, are 

 some fossil substances which seem to belong to this genus, and a 

 minute coralline substance resembling cellepora pumilosa, is fre- 

 quently seen on some of the fragments of encrinites, in the neigh- 

 bourhood of Bath. 



The genus Isis, the generic characters of which are, the possessing 

 a stony articulated stem, the joints longitudinally striated, connected 



