In 1925 Professor A. E. Trueman handed to the writer a copy of Professor Bertrand's paper, “Les Zones Végétales du Terrain Houiller du Nord de la France” (1914, p. 208), with the suggestion that it would be interesting to find out whether the succession of plants in South Wales is similar to that of the North of France, and to determine whether Bertrand's zones can be applied to the Coal Measures of South Wales. Since that time every opportunity has been taken to collect fossil plants from known horizons in South Wales and other coalfields. In addition, specimens have been examined in all the important museums and private collections, and in particular in the collections of the late Dr R. Kidston, which are now preserved in the Museum of Practical Geology.

The present paper deals with those non-marine shells which occur in the upper part of the Coal Measures: namely, in the Phillipsi and Tenuis Zones and in the higher portion of the Pulchra Zone. Those studies of the non-marine Lamellibranchs of the Coal Measures which have recently been published, have been directed chiefly to shells from the lower portion of the Coal Measures (Davies & Trueman, 1927; Wright, 1929; Clift & Trueman, 1929; and Hopkins, 1928, 1929). The shells which occur in the upper portion of the Coal Measures are mostly species of the genus Anthracomya, which have hitherto afforded evidence for no more than a broad classification of those measures; in the following pages we have attempted to define with greater precision the characters and ranges of these species. These investigations have been carried out with the assistance of grants from the Department of Scientific and Industrial Research, and we are particularly grateful for the generous way in which the Council of that Department has supported the work. One of us (A. E. T.) also wishes to acknowledge a grant from the Royal Society, which has defrayed certain expenses incurred during the early stages of the investigation. Most of the material described in the paper we have ourselves collected, and we wish to express our indebtedness to mine-owners and others for the cordiality with which we have been assisted in the various coalfields where collecting has been done. We have also had the advantage, through the kindness of Dr.

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Allergenic mites are responsible for inducing hypersensitive reactions in genetically predisposed people worldwide. Mites in dust from 30 Irish homes with pets (dogs, n = 23; cats, n = 7) were compared with those in 30 homes without pets. House dust mites constituted 78% of all mites recorded, with Dermatophagoides pteronyssinus (Acariformes: Pyroglyphidae) representing 57-72% of mites in furniture and mattresses in both home types compared with only 22% of mites in pet beds. Although storage mites accounted for just 13% of all mites recorded, they represented 46% of mites recorded in pet beds. Median levels of the dust mite allergen Der p 1 (µg/g) in dust samples from mattresses in homes without pets were significantly greater than in mattresses from homes with pets, reflecting the greater densities of D. pteronyssinus found in the former home category. Mite species richness was greater in homes with pets (17 species) than in homes without pets (13 species). This suggests that although the presence of pets can result in a wider variety of epidemiologically important mite species within households, increased competition among mite species may result in a more balanced mite fauna in the home, inhibiting the dominance of any one species and hence lowering allergen-associated risks.

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