The three masses of Dirrington Great Law, Dirrington Little Law, and Blacksmill Hill consist of riebeckite felsite, closely allied to the rock of the neighbouring Eildon Hills and most probably contemporaneous with it, i.e. they are of a Carboniferous age. They may represent the denuded remains of a laccolith which has been intruded into upper Old Red Sandstone conglomerates. The fourth mass forming Kyleshill is an orthophyre, with which is associated an andesite. The relations of these two rocks are obscure, and they may, or may not be, of the same age as the other three masses.

The previous literature on the pre-Cambrian rocks of Ireland is considerable in amount. The views of the early workers are briefly referred to in the Handbook of the Geology of Ireland, by G. A. Cole and T. Hallissy, published in 1924. This work doubtless expresses the opinion of Irish geologists of the present day.

Two papers bearing the same title have recently appeared in this magazine on the geology of Mangaia and Rurutu, two small islands located in the western part of the South Pacific Ocean.

It is unusual to discover specimens of Palaeozoic Brachiopoda which clearly display the characters of the delthyrium; in particular, very little is known concerning these features in Carboniferous Protremata. The writer has therefore been fortunate in obtaining well-preserved examples of Chonetes, in which the ventral pseudodeltidium and the dorsal cardinal process are exhibited in detail. It has also been found possible to determine the internal features of these structures by means of serial sections.