THE 
ORIGIN OF VERTEBRATES 
WALTER HOLBROOK GASKELL 
M.A., M.D. (CANTAB.), LL.D. (EDIN. AND MCGILL UNIV.) ; F.R.S.; FELLOW OF TRINITY 
HALL AND UNIVERSITY LECTURER IN PHYSIOLOGY, CAMBRIDGE ; HONORARY FELLOW 
OF THE ROYAL MEDICAL AND CHIRURGICAL SOCIETY; CORRESPONDING MEMBER 
OF THE IMPERIAL MILITARY ACADEMY OF MEDICINE, ST. PETERSBURG, ETC. 
LONGMANS, GREEN, AND CO. 
39 PATERNOSTER ROW, LONDON 
NEW YORK, BOMBAY, AND CALCUTTA 
1908 
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