ZOOLOGY MOLLUSCS The physical structure of the county of Leicester ought to be favourable to molluscan development, being well diversified ; and if the portion to the west of the Soar, where the Trias comes to the surface, affords less favourable soil than the secondary rocks to the east of that river, the Great Chalky Boulder Clay, which covers much of the central as well as the eastern por- tions of the county, should largely equalize matters for the land snails. The water drainage, on the other hand, is so extensive and varied that many suitable habitats are afforded for the water snails. Nevertheless the county has been rather neglected by malacologists in fact only two papers of any note have appeared on its molluscan fauna: one by J. Plant, compiled in 1850, but only brought to light and published in 1887;* and the other by H. E. Quilter detailing the specimens found by him between 1885 and 1887,* which practically formed the basis of the list in the Records of the Conchological Society. This last, however, did not include results from what might be expected to prove the most pro- ductive districts. We are further indebted to Mr. A. R. Horwood of the Leicester Museum for notes principally of additional localities. Altogether 92 species out of the 146 or so recorded for the British Islands, have been met with in Leicestershire, and this is a very fair average. The number will probably be further increased when more extended re- searches shall have been made, especially in the limestone districts. Two, or three, more species of slugs, several of the small Vertigos, as well as some other species ought certainly to be found in the district. Plant's record of Zonites lucidus has had to be rejected on account of the uncertainty attaching to the identification of the species so designated. It certainly had nothing to do with the Vitrea lucida now recognized as British. The records of Clausilia laminata prove so far to be errors for C. bidentata and have been omitted. An attempt was made without success to introduce the Roman snail (Helix pomatia) into the county, in 1845, when a number of specimens was turned out near Leicester ; but no survivors have been recorded though dead shells have been gathered. Owing to Leicestershire's central position none of the more typical northern, western, or southern species are present. The nomenclature adopted in the following list is that of the Con- chological Society issued in 1904, and differs from that employed in the earlier county histories of this series. Where the names here used differ from those previously given, the latter are added in square brackets in order to facilitate comparison. 1 Tram. Leic. Lit. and Phil. Soc. i, pt. 2, pp. 22-33. ' Op. cit. i, pt. 7, pp. 17-21 ; pt. n, p. 36. 61
