gratefully acknowledged; to Mr. Robert Standen and Mr. J. Ray Hardy he is under obligation for many striking facts and the loan of specimens, to Mr. G. K. Gude and Mr. R. W. Goulding for the preparation of several translations, and to Mr. C. T. Musson for permission to use a manuscript work on the "Land and Fresh-water Shells of Nottinghamshire," containing excellent essays on local distribution and means of dispersal. To Dr. Alfred Russel Wallace, who, with great kindness, has looked over the proofs and contributed the foregoing preface, the writer owes a special and irredeemable debt of gratitude. With a view to the collection of further facts illustrating the means of dispersal possessed by molluscs and allied animals, Dr. Wallace has suggested that the writer should invite "naturalists and sportsmen in all parts of the world" to co-operate by furnishing notes of, or references to, observations which they may have made or recorded, or which they may be able to make or record in the future. Many persons, both at home and abroad, he imagines, would make observations "if they knew what was wanted, and had the address of some one who would appreciate and use them." It may be mentioned that, amongst other things, the examination of large numbers of floating trees, etc., encountered upon the ocean, and of drift-timber and brushwood found stranded upon the coast-line, would possibly be productive of surprising results, as also would the careful and systematic inspection of the feet and feathers of birds shot on the wing. It is desirable, moreover, that search should be made for living mollusca in the crops of birds and in the stomachs of other shell-eating creatures. It need hardly be added that communications with which the writer may be favoured will be welcomed at the under-mentioned address, and carefully acknowledged. 5, Giesbach Road, Upper Holloway, London. September, 1893. H. W. K. |