Excerpt from Palaeontographical Society, Vol. 41: Issued for 1887
UP to a comparatively recent period so few genuine fossil Sponges were known from the older stratified rocks of the British area, that it would have been super ﬂuous to devote a separate portion of a Monograph especially to their consideration. Even now the number of species is very limited in comparison with those from the Mesozoic strata, and their state of preservation is very unfavorable; but recent discoveries show that Sponges as a group ﬂourished to such an extent in certain epochs of the Palaeozoic era as to form by their remains massive beds of rock of considerable thickness, and, measured by this scale, they were then more numerous than at any subsequent geological period.
In view of this enormous development of Sponge-life, it is reasonable to suppose that the small number of species known hitherto falls far short of those which then existed. In no group of organisms with structures capable of preservation have the inﬂuences of fossilisation acted with more destructive effect than upon fossil Sponges; at all events, on those in the Palaeozoic rocks; for thick beds occur built up almost exclusively of their remains, and yet not a single entire individual has been preserved in them! Their elaborate skeletal tissues have been altogether disintegrated, and only their minute, microscopical, spicular elements, heterogeneously mingled and cemented together into hard rock, remain for examination.
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