MAY 8; 



:^.^^ 



New Series, No. 197 (Vol. 50, Part 1). 



APRIL, 1906. 



Price 10s. net. 



THE 



QUARTERLY JOURNAL 



OP 



MICROSCOPICAL SCIENCE. 



EDITED BY 



E. KAY LANKESTER, M.A., D.Sc, LL.D., F.R.S., 



OF 



i-ow of exeteb c om.ege , ox fo b 1) j cork 

 thk impkiliaii academy of sciences oh 3t. 

 sciences ok philadelphia, and of the 

 ti'rin; foreign member of the UC 

 ottingen, and of the royal bohemian 



ISP ON DENT OF THE INSTITUTE OF FRANCJ 

 PETERSBURG, AND OF THE ACADEMY 

 ROYAL ACADEMY OF SCIENCES 



AL SOCIETY OF SCIENCES OF 

 SOCIETY OF SCIENCES, AND 



DI RECTO 

 LATE LI 



OF TUE ACADEMY OF THE LINCEI OF ROME, AND OF TUH AMERICAN 

 ACADEMY OF ARTS AND SCIENCES OF BOSTON t ASSOCIATE OK THE 

 nOYAL ACADEMY OF BELGIUM: HONORARY MEMBER r>F THE 

 NEW YORK ACADEMY OF SCIENCES, AND OF THE 

 CAMBBIDGE PHILOSOPHICAL SOCIETY, AND OK 

 THE ROYAL PHYSICAL SOCIETY OF BDIN* 

 BURGUi AND OF THE 

 BIOLOGICAL SOCIETY OF FARIS, AND OF TUB CALIFORNIA ACADEMY OF SCIENCES OF SAN FRANCISCO; 

 FOREIGN ASSOCIATE OF THE NATIONAL ACADEMY OF SCIENCES* U.S., AND MEMBER OF 

 THE AMERICAN P HILOSOPUICAL SOCIETY ; 

 THK NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM", LATE FULLKRIAN 

 PROFESSOR OK PHYSIOLOGY IN THE ROYAL INSTITUTION OF GREAT BRITAIN ; 

 ACRE PROFESSOR OF COMPARATIVE ANATOMY AND FELLOW OF MERTON COLLEGE, OXFORD. 



WITH THE CO-OPERATION OF 



ADAM SEDGWICK, M.A., F.R.S., 



FELLOW AND TUTOR OF TRINITY COLLEGE, CAMBRIDGE ^ 



W. F. R. WELDON, M.A., F.R.S., 



SYDNEY J. HICKSON, M.A., F.R.S., 



BEYEB PKOFliSSOH OF ZOOLOGY IN THE OWENS COLLEGE, MANCHESTER. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES. 



LONDON: 



J. & A. CHCJECHILL, 7 GEE AT MARLBOROUGH STREET. 



1906. 



Adlardancl Son, Impr.,] 



[London and Dorkin^ 



