176 Mr. H. J. Carter on a Fossil Species 



Polytrema. For Oculina rosea, in the paper first mentioned, 

 read Stylaster sanguineus. 



I have also lately found pieces of coral-detritus rock both 

 from Jamaica and the Mauritius, almost covered with fragments 

 of Polytrema miniaceum and Carpenteria utricularis, mixed 

 together indiscriminately^ thus presenting respectively in their 

 broken summits a very similar appearance, especially where 

 each utricle of the Gar-penteria (which is often the case) ap- 

 pears to have been provided with its own branched tubular 

 prolongation. 



XXV. — On a Fossil Species of Sarcohexactinellid Sponge 

 allied to Hyalonema. By H. J. Carter, F.K.S. &c. 



About the 23rd of June last I had the pleasure to receive 

 from Mr. James Thomson, F.G.S. &c., of Glasgow, for deli- 

 neation and description, if thought desirable, a box of fossils 

 from the Carboniferous rocks of Scotland, which " for many 

 years " Mr. Thomson had regarded as belonging to the 

 sponges ; and among these is a fragment of rock bearing 4-5 

 inches of the anchoring lash of spicules respectively of two 

 specimens of apparently the same sarcohexactinellid sponge, 

 which Mr. Thomson views provisionally as having belonged 

 to a " Hyalonema^ Besides these there are other specimens 

 of this kind mixed up with sexradiate spicules of various forms; 

 but particularly a fragment where some of these spicules are 

 evidently nearly in situ, which leaves no doubt in my mind 

 that this was a portion of the body of a sarcohexactinellid 

 sponge. 



I had, through the great kindness of Dr. J. Millar, become 

 possessed, about a year since, of some of these hexactinellid 

 spicules, as well as fragments of the linear spicules, which I 

 now find to have come from anchoring ones similar to those 

 of the '' lash " just mentioned ; and these were of the same 

 kind as those exhibited before the British Association at Glas- 

 gow last year, where they were called " Acanthaspongia 

 Smithiiy 



The name of AcantJiaspongia siluriensis was proposed by 

 M'Coy for the fossil remains of a sponge in the collection of 

 Mr. R. Grifiith, F.G.S., obtained from tlie sandstone of Cong, 

 county Galway ; and the specimen (for there is no figure of 

 it) is described (' Synopsis of the Silurian Foss. of Ireland,' 

 p. 67, 1846) as consisting of " a lengthened oval mass, about 

 two inches long and three fourths of an inch wide, of crowded 



