TRANSCRIBER’S NOTES: —Obvious print and punctuation errors were corrected. —Underlined text has been rendered as *underlined text*. The Cambridge Manuals of Science and Literature THE FLEA CAMBRIDGE UNIVERSITY PRESS London: FETTER LANE, E.C. C. F. CLAY, MANAGER [Illustration: LOGO] Edinburgh: 100, PRINCES STREET London: H. K. LEWIS, 136, GOWER STREET, W.C. WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND Berlin: A. ASHER AND CO. Leipzig: F. A. BROCKHAUS New York: G. P. PUTNAM’S SONS Bombay and Calcutta: MACMILLAN AND CO., LTD. _All rights reserved_ [Illustration: _After a drawing by Dr Jordan_ Oriental rat-flea (_Xenopsylla cheopis_ Rothsch.). Male.] [Illustration; DECORATED FRONT PAGE: THE FLEA BY HAROLD RUSSELL, B.A., F.Z.S., M.B.O.U. With nine illustrations Cambridge: at the University Press 1913] Cambridge PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS _With the exception of the coat of arms at the foot, the design on the title page is a reproduction of one used by the earliest known Cambridge printer, John Siberch, 1521_ PREFACE THE aim of this book is to give in plain language some account of a small, but noteworthy, group of insects. I have avoided, whenever I could, using the technical terms of zoology. To avoid doing so entirely is impossible in a book which describes insects in some detail. No technical term has, I hope, been used without an explanation. Over thirty years have elapsed since Taschenberg’s German book, _Die Flöhe_, appeared. Our knowledge has made enormous strides since then. More species of flea are now known from the British Islands alone than were then known from the whole world. So far as I am aware, no book, devoted to what is known about fleas, has ever been published in English. The statements about these insects in the general text-books of entomology are frequently antiquated and inaccurate. But there is a fairly extensive literature on the _Siphonaptera_ scattered through scientific periodicals mostly in English, German, Italian, Dutch and Russian. I have given some references in the Bibliography.