/ /^ TEXT-BOOKS OF ANIMAL BIOLOGY Edited by Julian S. Huxley, M.A. FuUerianProfessorofPhysiology, RoyalInstitution; HonoraryLecturer, King'sCollege,London. ANIMAL ECOLOGY TEXT-BOOKS OF ANIMAL BIOLOGY Edited byJulian S. Huxley COMPARATIVE PHYSIOLOGY. By L. T. HOGBEN, m Othervolumes pfeparation. VERTEBRATE MORPHOLOGY. By C. R. DE Beer. EXPERIMENTALZOOLOGY. ByJulian S. Huxley. ANIMALMORPHOLOGY,WITHESPE- CIAL REFERENCE TO THE IN- VERTEBRATA. By W. Garstang. ANIMAL ECOLOGY BY CHARLES ELTON WITH AN INTRODUCTION BY JULIAN S. HUXLEY, M.A. FULLERIAN PROFESSOR OF PHYSIOLOGY,ROVAL INSTITUTIOV NEW YORK THE MACMILLAN COMPANY 1927 PRINTED IN GREAT BRITAIN BY WILLIAM CLOWES AND SONS, LIMITED LONDON AND BECCLES.