iUN 30 1906 



New Series, No. 198 (Vol. 50, Part 2). 



JUNE, 1906. 



Price 10s. net, 



THE 



QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



EDITED BY 



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



HONORARY FKI.LOW OK KXKTER COM.KGK , OXf OR D ; CORRESPONDKNT OF THE INSTITUTE OK PRANCK 

 AND OF THE IMPERIAL ACADEMY OK SCIENCES OF ST. PETERSBURG, AND OF THE ACADEMY 

 OF SCIENCES OF FHILADELP IIIA. AND OF THE ROYAL ACADEMY OF SCIENCES 

 OF TURIN; FOREIGN MEMBER OF THE ROYAL SOCIETY OP SCIENCES OF 

 GOTTINGEN, AND OF THE RUYAL BOHEMIAN SOCIETY OF SCIENCES, AND 

 OF THE ACADEMY OF THE LINCEI OF ROME, AND OK TUK AMERICAN 

 ACADEMY OF ARTS AND SCIENCES OF BOSTON ; ASSOCIATE OF THE 

 ROYAL ACADEMY OF BELGIUM; HONORARY MEMBER nF THE 

 NEW YORK ACADEMY OF SCIENCES, AND OP THE 

 CAMBRIDGE PHILOSOPHICAL SOCIETY, AND OF 

 THE ROYAL PHYSICAL SOCIETY OF EDIN- 

 BURGH* AND OF THE 

 BIOLOeiCAL SOCIETY OF PARIS, AND OF THE CALIFORNIA ACADEMY OF SCIENCES OF SAN FRANCISCO; 

 FOREIGN ASSOCIATE OF THE NATIONAL ACADEMY OF SCIE NCES, U.S., AND MEMBER OF 

 THE AMERICAN PHILOSOPHICAL SOCIETY ; 

 DIRECTOR OF THE NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM; LATE FULLRRIAN 

 PROFESSOR OF PHYSIOLOGY IN THE ROYAL INSTITUTION OP GREAT BRITAIN; 

 LATE LINACRE 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; 



AND 



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



BEYER PROFESSOR OF ZOOI.UGI IN IHF, 0WEX3 COLLEGE, MASCUE8TKR. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES. 



LONDON : 



J. & A. CHURCHILL, 7 GREAT MARLBOROUGH STREET. 



1906. 



Adlard and Son, Impr.,] 



[London and Dorking. 



