Carter — Fossil Sponge-Spicules from Ben Bulben. 1 9 1 
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. S. 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 Fora- 
minifera, viz. : — 1, containing no organisms ; 2, a few Foraminifera and spi- 
cules ; 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 interstratified with bands of chert, especially at 
the summit of the mountain, where it is very soft, owing, apparently, to 
exposure 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 carefully looking over all that he found, which were subse- 
quently forwarded to me, I can add no more specifically, although I have been 
able to find a few with slightly different forms, which have assisted me in the 
following descriptions. Of course, as drift-spicules, which these must have 
been when originally deposited, to say nothing of the subsequent effects of 
fossilization, &c., they are nearly all fragmentary ; but sufficient of them 
remains for easy recognition and for restoration, as will be seen by the illus- 
trations. 
First and foremost is a sexradiate stellate (PI. XIV. B. fig. 2), which in 
