This is the first of a series of contributions dealing with various aspects of the petrology of Barnavave Mountain which have not been touched upon by earlier investigators. The general relationships existing between the various rock types on Barnavave were first described by Traill in 1878, though some of the rock types had been previously dealt with by Haughton. This was followed by the now classical work of Sollas on some of the hybrids occurring on the western side of the mountain. These are at present being redescribed by Dr. G. D. Osborne in a paper which will appear shortly. More recently, the Carlingford area as a whole has been dealt with by Richey and Osborne has described the metamorphosed limestones of the region. Many of the rock types, however, have never been described in detail, if at all, and it is with these that the present contributions are concerned. The author wishes to express his thanks to Prof. W. J. Pugh, Prof. C. E. Tilley and Dr. G. D. Osborne for facilitating the work in various ways, to acknowledge a grant from the Worts fund and a Royal Society grant which defrayed the cost of two of the analyses. The field work was carried out in 1932 but unforeseen circumstances prevented the earlier working up and publication of the results.

In 1825 J. de C. Sowerby described and figured as Spirifer lineatus a brachiopod from the “ Wenlock Limestone ” of Dudley, choosing three syntypes; later he changed the specific name to radiatus. Of subsequent descriptions those of Hall (1852), Davidson (1866), Beecher and Clarke (1889), and Hall and Clarke (1894) are the most important. The present study is based on topotype material, while additional specimens for comparison have been collected by the writer from the Wenlock Shale of Malvern (Colwall Tunnel Tip Heap), from the Woolhope Limestone of Suckley, from the Wenlock Limestone of May Hill, and from the Tickwood beds and Wenlock Limestone on Wenlock Edge (railway cuttings near Presthope and Lilleshall Quarry). These, together with specimens from the Sedgwick Museum Collection, from the Birmingham University Collection, and from the British Museum (Natural History), have provided material adequately representative of variations in shape and size. Study has been made of external features, but more particularly of internal characters. The method of investigating the internal structures consists in grinding down the specimen either from the umbones, or from the lateral margin, and taking serial cellulose transfers at regular intervals, from which enlarged scale models may be constructed. Five specimens have been so treated, and as well as the construction of models, use has been made of perspective scale drawings to show the variations in internal structure. Growth lines are preserved on the transfers, but have in addition been examined in thin sections; specimens from Haverfordwest and Rubery preserved as casts have served to throw light on the muscle system, while finally the ventral valves of specimens preserved in shale, have been prepared to show the variations in internal structure.

The series of estuarine deposits which occurs at Kirmington, North Lincolnshire, situated between Brown Boulder Clay and Purple Boulder Clay, has long been recognized as of considerable importance owing to its inter-glacial position. The best description of the complete sequence of beds overlying the Chalk at this locality has been afforded by a Committee of the British Association (1).