Palæontological Notes [on Ordovician Fossils from the Glensaul District]

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Abstract
The fossils from this district which have been submitted to me for determination are mostly poor and fragmentary. They occur in two main types of rocks: namely (i) a hard, coarsely crystalline, reddish limestone (97, 155), and (ii) a rotten, gritty, calcareous ash (62). The specimens from the limestones marked 97 & 155 apparently belong to the same horizon and come from the same bed at different localities, for the rocks are lithologically identical and the faunas are indistinguishable. This horizon may be unhesitatingly correlated with the limestone of the Tourmakeady Beds described on a previous occasion. The more abundant material and newly discovered members of the fauna from these Glensaul localities necessitate a slight revision of my views as to the age of the limestone, and the additional evidence now available points to a somewhat lower horizon than was previously considered to be indicated. In fact, it appears that we must now correlate it with the Scandinavian equivalent of the English Arenig, that is, with the main mass of the Orthoceras Limestone. My previous reluctance to place the beds so low was due to the insufficiency of the evidence derived from the fossils; but now there does not appear to exist sufficient ground for refusing to admit that the sediment accumulating here in Arenig times was temporarily of a calcareous nature, and that the fauna which flourished during that interval in the West of Ireland was closely similar to that of the Scandinavian seas, where identical physical conditions of

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