[On the Fauna of the Tourmakeady Rocks]

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Abstract
A. General Remarks on the Fauna. (1) The Limestone (Tourmakeady Beds).—The fauna of the limestone is not rich in species, but the fragmentary nature of the organic remains is the main obstacle to a satisfactory knowledge of its characteristics. Members of the genus Illœnus seem to be the most abundant fossils. In spite of the matrix and mode of preservation of the fossils resembling those of the Chair of Kildare and Keisley, the facies of the fauna must be regarded as indicating a considerably lower horizon, for not only are the typical species of the Upper Bala l absent, but the assemblage is not that of the Middle Bala, and certain genera and representative species which occur m it are outv known elsewhere from beds correlated with the Lower Bala (Llal{deilo). Of such fossils we may especially note the species of Pliomera and Porambonites . The genus Pliomera occurs abroad only in the lower part of the Ordovician— on horizons generally regarded as homotaxial with the Arenig and Lower Bala. Such is the case in Scandinavia, the Baltic provinces of Russia, and North America, while in Scotland and Ireland it is found only in the Craighead (Stinchar) Limestone and in the Tramore Limestones respectively, which are believed to lie considerably below the Middle Bala. No undoubted representative of the genus from beds of later age than Lower Bala is definitely known. The same remarks apply to the genus Porambonites , which is especially characteristic of the lower stages of the Ordovician in the Baltic region. The evidence

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