A Revision of the Non-Marine Lamellibranchs of the Coal Measures, and a Discussion of their Zonal Sequence

Abstract

The present paper deals with those Coal Measure lamellibranchs that are referred to the genera Carbonicola, Anthracomya , and Naiadites . These genera are represented at many horizons in the Coal Measures of Western Europe; they are now generally regarded as being of estuarine or freshwater habit, and it may be considered as established that they are not ordinarily associated with any of the marine forms which are found at certain horizons in the Coal Measures. In this country the most important advances in the study of these shells resulted from the work of the late Dr. Wheelton Hind (1893, 1894–96, 1904), who systematized the classification, and demonstrated the utility of various species in correlating coal-seams and in zoning the Coal Measures, especially of Staffordshire. Wheelton Hind published a critical bibliography of these shells in 1894, and it is therefore unnecessary to repeat here the history of research before that date. Reference is incidentally made to subsequent publications in the following pages, but it may briefly be noted that, apart from notable contributions by the late John Ward (1905), Dr. H. Bolton (1911, 1915), and others, the use of these shells in the correlation of the Coal Measures has been neglected in this country until recent years. It has been suggested that, for various reasons, they are less reliable in zoning than the plants. Owing to the labours of Hind and Ward, the sequence of these mollusca has been better known in the North Staffordshire coalfield than in any other British coalfield;