The principal descriptions and figures of the Ordovician and Silurian brachiopods of the Girvan district are found in Davidson's Monograph on the British Fossil Brachiopoda, completed about thirty years ago, and issued by the Palæontographical Society. The third volume of this work (published 1866–1870), and the Supplement to the fifth volume (published 1882–1883), dealing with species from Ordovician and Silurian beds, contain descriptions of many Girvan forms, but not apart from those occurring in other British localities. No independent and comprehensive treatise on this group as represented in the Girvan area has been published, though many short papers have dealt with a few species or portions of the fauna. Especially noteworthy are the papers and works by M'Coy and Salter, mentioned in the list at the end of this memoir.

The investigations recorded in this communication were begun some years ago, and arose chiefly as the result of two papers published on the Geology of the Forest of Wyre by Mr T. C. Cantrill, B.Sc.

In the latter paper Mr Cantrill, after carefully summarising all the available data respecting the age of the so-called “Permian” of the Forest of Wyre (= Enville), arrives at the following conclusions:—

I. That these “Permian” rocks are of the same age as those at Hamstead in South Staffordshire.

II. That the Hamstead red rocks were shown by their flora to be Upper Coal Measures.