Extract
In the course of examination of the non-marine lamellibranchs from British Carboniferous rocks I have for several years noted all instances of the attachment of the tubes of Spirorbis. The observations which have been made confirm the conclusions of Pruvost (1919, p. 32; 1930, p. 257) that Spirorbis in the Coal Measures is frequently found attached to plants, occasionally to marine shells, and more commonly to non-marine lamellibranchs. Of the latter, Naiadites and Anthraconauta show the greatest number of attachments; attachments to Carbonicola are not uncommon, but Spirorbis is rarely, if ever, attached to Anthracomya. Over 80 per cent of the attachments recorded by the writer from the Lower Westphalian relate to Naiadites, practically all the remainder relating to Carbonicola; in many instances, however, there were great numbers of Spirorbis attached to individual specimens of Naiadites whereas the numbers in the case of Carbonicola were generally much smaller. In the Upper Westphalian attachment to Anthraconauta is very common, and the similarity of Anthraconauta and Naiadites in this respect was urged by Pruvost as one evidence of their presumed relationship and as justification for separating Anthraconauta from Anthracomya (1930, p. 223). These conclusions I am able to endorse from these observations.