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resembling the state in which it exists in chalk-flints and greensand 
cherts, and to the variations in its colouring matter the banded ap- 
pearance of the jaspers is due. Imbedded, but very unequally in 
the layers composing the jaspers, Mr. Bowerbank discovered hun- 
dreds of beautiful foraminifera closely resembling those found in 
chalk-flints, and often difficult to distinguish from the species found 
in the Grignon sand of the calcaire grossier. 
The Mocha stones which the author has examined, presented no 
indications of organic structure, the moss-like delineations and other 
appearances, resembling beautiful, thin, reticulated tissues, being due 
to dendritical or metallic infiltrations. 
In the larger pebbles of a mass of Herefordshire pudding-stone, 
Mr. Bowerbank discovered the characteristic spongeous structure of 
chalk-flints. 
In conclusion, the author dwells upon the difficulties attending 
the study of the bodies which he has examined and described, in 
consequence of the little attention which has been paid, with few 
exceptions, to the structure of recent sponges; and he states that - 
the aspect of the latter, when viewed by the unassisted eye, is so 
different from that which it presents when seen under a high micro- 
scopic power, that those who have not been accustomed to study 
recent sponges with that aid would never recognise a similar struc- 
ture im the fossils described by him. He also shows that the pre- 
valence of keratose sponges over those belonging to the genus Hali- 
chondria is what might naturally be expected, as the spicula which - 
form the skeleton of the latter would be less likely to be preserved 
in their original position than the horny fibres of the former. 
Lastly, the author alludes to the great share which sponges have 
had in the production of the solid strata of the earth’s crust, 
Among the donations presented to the Society's Museum and an- 
nounced at this Meeting, were the following :— 
A series of fossils from the mountain-limestone of the county of Kildare, 
presented by the Earl of Enniskillen, including 
Amplexus Sowerbii. Terebratula reniformis. 
Retepora? laxa. ——_———— resupinata. 
Fenestella membranacea. Spirifera glabra. 
Cheetetes. — pinguis. 
Asaphus obsoletus. ~— rotundata. 
Isocardia oblonga. ———-— attenuata. . 
Producta sulcata. Pileopsis vetusta. 
Martini. -Euomphalus pentangulatus. 
scabricula. Orthoceras giganteum. 
hemispherica. ——— inequiseptum ? 
analoga. Nautilus cariniferus. 
Terebratula hastata. —— dorsalis. 
cordiformis. ————— compressus. 
platyloba. 
Remains of the Mammoth, found in a gravel-pit in the parish of New- 
ington, near Sittingbourne. Presented by William Bland, Esq. 
Graptolites from Clarbeston, six and a half miles N.E. of Haverfordwest, 
Pembrokeshire. Presented by W. H. Scourfield, Esq. 
