CAMBRIDGE BIOLOGICAL SERIES. GENERAL EDITOR:--ARTHUR E. SHIPLEY, M.A. FELLOW AND TUTOR OF CHRIST'S COLLEGE, CAMBRIDGE. THE VERTEBRATE SKELETON. London: C.J. CLAY AND SONS, CAMBRIDGE UNIVERSITY PRESS WAREHOUSE, AVE MARIA LANE, AND H.K. LEWIS, 136, GOWER STREET, W.C. [Illustration] Glasgow: 50, WELLINGTON STREET. Leipzig: F.A. BROCKHAUS. New York: THE MACMILLAN COMPANY. Bombay and Calcutta: MACMILLAN AND CO., LTD. [_All Rights reserved._] THE VERTEBRATE SKELETON BY SIDNEY H. REYNOLDS, M.A., TRINITY COLLEGE, CAMBRIDGE; LECTURER AND DEMONSTRATOR IN GEOLOGY AND ZOOLOGY AT UNIVERSITY COLLEGE, BRISTOL. Cambridge: AT THE UNIVERSITY PRESS. 1897 [_All Rights reserved._] =Cambridge=: PRINTED BY J. & C.F. CLAY, AT THE UNIVERSITY PRESS. PREFACE. IN the following pages the term skeleton is used in its widest sense, so as to include exoskeletal or tegumentary structures, as well as endoskeletal structures. It was thought advisable to include some account of the skeleton of the lowest Chordata--animals which are not strictly vertebrates, but it seemed undesirable to alter the title of the book in consequence. The plan adopted in the treatment of each group has been to give first an account of the general skeletal characters of the group in question and of its several subdivisions; secondly to describe in detail the skeleton of one or more selected types; and thirdly to treat the skeleton as developed in the group organ by organ. A beginner is advised to commence, not with the introductory chapter, but with the skeleton of the Dogfish, then to pass to the skeletons of the Newt and Frog, and then to that of the Dog. After that he might pass to the introductory chapter and work straight through the book. I have endeavoured to make the account of each type skeleton complete in itself; this has necessitated a certain amount of repetition,--a fault that I have found it equally difficult to avoid in other parts of the book. Throughout the book generic names are printed in italics; and italics are used in the accounts of the type skeletons for the names of membrane bones. Clarendon type is used to emphasise certain words. In the classificatory table the names of extinct genera only, are printed in italics.