210 Mr. H. J. Carter on Fossil Sponge- spicules. 



(ibid. p. 145) some observations on specimens of limestone 

 belonging to the Carboniferous series which Mr. Thomson 

 had gathered from the western side of Black Head, county- 

 Clare, at the southern extremity of the entrance to Galway 

 Bay, in which the siliceous element (often present in great 

 quantity) seemed to indicate that it had been derived from 

 some organisms more or less composed of silica, especially as 

 in other parts, where the limestone is pure, the remains of 

 sponge-spicules in a calcified state are abundantly recognizable, 

 although in none of the specimens sent to me could I find a 

 definite form. 



Here the matter rested, so far as I myself was concerned ; 

 but Mr. Joseph Wright, F.G.S., who resides at Belfast, 

 having subsequently visited the mountain near Sligo called 

 " Ben Bulben," actually ascertained the presence of several 

 forms of sponge-spicules in the limestone of the Carboniferous 

 system there, and kindly forwarded specimens of them to me, 

 together with fragments of the strata in which they are found, 

 for description and illustration. But before I proceed to this, 

 it is desirable that the following extracts from Mr. Wright's 

 letter, dated Jan. 1, 1880, which accompanied them, should 

 be given, viz. : — 



" Last summer my friend Mr. fe>. A. Stewart spent a few 

 days botanizing on Ben Bulben, and, whilst there, observed 

 soft clay bands in the limestone, of which he brought me 

 three different ' gatherings ' to examine for Foraminifera, 

 viz. : — 1, containing no organisms ; 2, a few Foraminifera 

 and spicules ; and 3, rich in sponge-spicules. 



" The last material proved so interesting that we afterwards 

 visited the place in company and brought away a quantity of 

 the clay. It is of a pale yellowish colour, and occurs interstra- 

 tified with bands of chert, especially at the summit of the 

 mountain, where it is very soft, owing, apparently, to expo- 

 sure to the weather ; on the other hand, lower down, the 

 same yellow material occurs, but much harder, although 

 lighter, from its open pumice-like structure. At both places 

 we found a great number of fossils belonging to the limestone 



of the Carboniferous system, viz 



" I sent some of the clay to a friend in Cork for analysis ; 

 and he has informed me that it contains 98 per cent, of 

 silica." 



After this follow sketches of all the forms of fossil sponge- 

 spicules that Mr. Wright by dexterous manipulation was 

 enabled to extricate from the clay — to which, after care- 

 fully looking over all that he found, which were subse- 

 quently forwarded to me, I can add no more specifically, 



