A MONOGRAPH 
CARBONICOLA, ANTHRACOMYA, AND NATADITES. 

§ I. INTRODUCTION.’ 
Tx fossils to be described in this Monograph are obtained, almost without 
exception, from the productive Coal-measures of the Carboniferous Series ; whether 
they occur, as in Scotland, the North of Ireland, and the North of England, at the 
base of this formation, as well as in the Coal-measures proper; or, as in the other 
coal-fields of Ireland, the remainder of England and Wales, and the Continent, 
above the Millstone-grit, in the upper beds. They chiefly occur in ironstone bands 
or nodules in indurated marl, and in black carbonaceous shales, and often in such 
profusion as to constitute shell-beds which extend over large areas. 
On the Continent it is found that the genera occurring in the Coal-measures 
pass up into beds of Permian age; but it is doubtful at present whether it can be 
shown that the same species survived through both periods. 
It is not within the scope of this Monograph to attempt the correlation of the 
various strata found in the different coal-fields of Great Britain ; indeed, the 
Author believes that it would be impossible to do so, from the fact that the nature 
and thickness of the coal-seams and intervening beds undergo such alterations in 
the same coal-field that the conditions affecting the deposit must have been very 
1 In working up the Bibliography of the bivalve Mollusca of the Coal-measures I have been 
reluctantly obliged to acknowledge that in two at least of the three genera to be described in this 
Monograph the names now in use must be abandoned for others which have the priority. M‘Coy’s 
name of Carbonicola, though accompanied by a partly erroneous diagnosis, is undoubtedly a few 
months older than King’s Anthracosia, in which, too, the hinge characters described belong to a 
species, and not to the genus. And also there is no doubt that Prof. J. W. Dawson’s Naiadites is 
older than Salter’s Anthracoptera, although Dawson’s genus originally contained members of all the 
genera to be described in this work. 
1 
