1 9 o Carter— Fossil Sponge-Spicules from Ben Bulben. 
almost purely silicious. Mr. Cooke regards it as disintegrated chert, the 
disintegrating agent being animal life. The following is Mr. Cooke s analysis i . 
su e , soluble and insoluble, 97 to 98 per cent. ; alumina, with -^ 0 
iron i per cent. ; lime, less than 1 per cent. ; traces of magnesia and man 
Zese 1-10 per cent. Mr. Cooke finds clear proof of organic matter stiU 
Listin’- in the clay, and he considers that the sUica was probably bj 
“olcanic outburst. In the « rotten limestone' » of Cunningham 
Ayrshire, which seems to resemble our Ben Bulben ® p ™ g . 6 " 9pl ™ f tl 
Abundant, and yery similar to those found in Sligo. In the Insh as^in the 
Scotch beds, chert occurs associated with the clays in w i . t to 
found. Thi is similar to what occurs in our Cretaceous recks, and points to 
the fact of the silica which forms our flints and chert haying ben, m part at 
least deriyed from silicious sponges which abounded in ancient seas, the sill 
being ^deposited in layers, or concentrated round some sponge « otbe 
organism, and so forming our nodular flints. The paper was lUuutated by a 
fine series of diagrams representing the various forms o spicules obtained 
the Sligo mountains, as well as the material in 
Several examples of recent and fossil sponges were also exhibited 
of the meeting. 
Through the kind permission of Mr. H. J. Carter, F R.S., the following 
paper, “ On fossil sponge-spicules from the Carboniferous strata of Ben Bulbe , 
has been reprinted from the Annals and Magazine of Natural Histo^ Sep ., 
1880 ■ the figures which accompanied it have been reproduced by photo-lith- 
ography, and are an exact reproduction of the originals. 
(From the Annals and Magazine of Natokal Hisrour/or Sept, 1880.; 
ON FOSSIL SPONGE-SPICULES FROM THE CARBONI- 
FEROUS STRATA OF BEN BULBEN, NEAR SLIGO. 
BY H. J. CARTER, F.R.S., &c. 
Plate VIII., (lower half) figs. 1-17. 
J N the last contribution that Mr. James Thomson made to our pledge > of 
fossil sponges which existed during the Carboniferous epo h m the 
neighbourhood of Glasgow (‘Annals,’ 1879, vol. m., p. !«, P'- » 
described and illustrated Holasterella conferta a genus of sponges, as the 
name indicates, exclusively composed of stelliform spicule , 3T 
figure, from tho same locality, had been found and illustrated a yea. ^previous y. 
M the same time I added (ibid. p. 145) some observations on specimens of 
