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New Series, No. 224 (Vol. 56, Part 4). Price lOs. net. 



Subscription per volume (of 4 pax'ts) 40s. net. 

 JUNE, 1911. 



THE 



QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



EDITK)) MV 



Sir ray LANKESTER, K.C.B., M.A., D.Sc, LL.D., F.R.S., 



HOr<OHAKT KBI.I.OW OK EXBTKR COM'KGB, OXFORD ; 

 MEMBER OF TUB I.N3TITUTK OK KH A NCE (aS.SOCI^ £t BANGER DE l'aCADEMIE DES SCIENCES) ; 

 CUHKESP0NUK:<T op THB IMPKRIAI, ACADKMV op SCIKNCES OF ST. PETKK8BURG, AND OP TUE 

 ACADKMY OP 8CIENCK8 OP P IIII.ADK I,P II I A , AND OK THE ROYAL ACADEMY OP SCIKNCES 

 OP TURIN; FOREIGN MEMBBR OP T II K KOYAl. SOCIETY OP SCIENCES OF 

 GOTTINGEN, AND OP THE RoYAI. BOHEMIAN SOCIETY OP SCIKNCES, AND 

 OP THE ACADEMY OP THE MNCEI OP ROME, AND OF TUB AMERICAS 

 ACADEMY OF ARTS AND SCIENCES OP BOSTON \ ASSOCIATE OP TUB 

 ROYAI. ACADEMY OP BELGIUM; HONORARY MEMBBR r.K THE 

 NEW YORK ACADEMY OF SCIENCES, AND OP THE 

 CAMBRIDGE P It I I.O S O F H IC AI. SOCIETY, AND OP 

 THE ROYAI. PlIYSICAl, SOCIETY OP EDIN- 

 BURGH, AND OF THB 

 BIOLOGICAL SOCIETY OP FAKIS, AND OF THK CALIFORNIA ACADEMY OF SCIENCES OP SAN FRANCISCO, AND 

 OF THE ROYAL ZOOLOGICAL AND M A L ACOLOGIC AL SOCIETY OP BELGIUM; 

 CORRESPONDING ME5IBER OP THE SENKENBERG ACADEMY OP PR AX KFURT'A-M ; 

 FOREIGN ASSOCIATE OP THK NATIONAL ACADEMY OP SCIENCES, U.S., AND MEMBER OP THE 

 AMERICAN FHILOSOFHIfAL SOCIETY; 

 HONORARY FELLOW OF THB ROYAI. SOCIETY OF EDINBURGH; 

 LATE DIHKCTOR OP THE NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM: LATE PRESIDENT OF THE 

 BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE; LATE FUI.LKRIAN PKOPESSOK OP 

 PHYSIOLOGY IN THK UoYAL INSTITUTION OP GREAT BRITAIN; 

 LATR LINACRE PROFESSOR OF COMPARATIVE ANATOMY AND FELLOW OP MERTON C OLLEGK , OX FOR D ; 

 EMERITUS PROFESSOR OF ZOOLOGY AND COMPARATIVE ANATOMY IN UNIVERSITY COLLEGE. UNIVERSITY OP LON DON 



WITH THE CO-OPEKATION OF 



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



FELLOW OF TRINITY COLLEGE, CAMBRIDGE. AND PROFESSOR OP ZOOLOGY IN THE IMPERIAL COLLEGE OP 

 SCIENCE AND TECHNOLOGY, LONDON; 



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



BEYER PROFESSOR OP ZOOLOGY IN THK UNIVERSITY OF MANCHESTKR; 



E. A. MINCHIN, M.A., F.R.S., 



PROFESSOR OP PB01 OZOOLOGY IN THE UNIVERSITY OK LONDON; 



AND 



GILBERT C. BOURNE, M.A., D.Sc, F.R.S., 



LINACRE PKOFKSSOK OF COMPAR^TIVK ANATOMY, AND PKLLOW OF MERTON COLLEGE, OXFORD. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES. 



LONDON. 

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



1911. 





Adiard and Son, Impr.,] 



1 [London and Dorking. 



