IBI 



New Series. No. 217 (Vol. 55, Part 1). Price lOs. net. 



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

 APRIL, 1910. 



rn 



THE 



QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



EDIIKI) HY 



SiE RAY LANKESTER, K.C.B., M.A., D.Sc, LL.D., F.R.S., 



HONUKABY KEI.LOW OF EXETER C O I.I-EG E , O X f (I U U ; C Oil U KS F O M» E S T OF THE INSTITUTE OF KKANCE, 



AND (IF THE IMPERIAL ACADEMY OF SCIENCES OF ST. FETEU8BUHG, AND OF T 11 E ACAUKiMY 



OF 8CIENCK3 OF P 11 1 1. AD E I.F 11 1 A , AND OF THE ROYAL ACADEMY OF SCIENCES 



OF Turin; foreign member of the royai. society of sciknces of 



GOTTINGEN, AND OF TUE KOYAI. BOHEMIAN SOCIETY OF SCIENCES, AND 

 OF THE ACADEMY OF THE I.INCEI OF ROME, AND OF THK AMKIUCAN 

 ACADEMY OF ARTS AND SCIENCES OF BOSTON ; ASSOCIATE OF THK 

 ROYAI- ACADEMY OF BELGIUM; HONORARY MEMBER oP THE 

 NEW YORK ACADEMY OF SCIENCES, AND OF THK 

 CAMRUIDGE PHILOSOPHICAL SOCIETY, AND OF 

 THE ROYAL PHYSICAL SOCIETY OF EDIN- 

 BURGH, AND OF THK 

 BIOLOGICAL SOCIETY OF PARIS, AND OF THE CALIFORNIA ACADEMY OF SCIENCES OF SAN FRANCISCO, AND 

 OK THK ROYAL ZOOLOGICAL AND M AL A COLO GIC A L SOCIETY OF BELGIUM; 

 CORRESPONDING MEMBEK OV THE 8ENKENBERG ACADEMY OF E R A N KFUBT-A'M ; 

 FOREIGN' ASSOCIATE OF THK NATIONAL ACADEMY OF SCIENCES. U.S., AND MEMBER OF THK 

 AMERICAN PHILOSOPHICAL SOCIETY ; 

 HONORARY FELLOW OF THE ROYAL SOCIETY OF EDINBURGH; 

 LATE DIRECTOR OF THK NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM ; LATE PRESIDENT OF THE 

 BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE; LATE FULLKltlAN PROFESSOR OP 

 PHYSIOLOGY IN THK ROYAL INSTITUTION OP GREAT BRITAIN ; 

 LATE LINACRE PROFESSOR OF COMPARATIVE ANATOMY AND FELLOW OF MEBTON C OLl.E GE , OXFO R D J 

 EMERITUS PROFESSOR OF ZOOLOGY AND COMPARATIVE ANATOMY ly UNIVERSITY COLLEGE, UNIVERSITY OF LONDON 



WITH THE CO-OPERATION OF 



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



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



SCIENCE AND TECHNOLOGY, LONDON. 



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



BEYER PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF MANCHESTER; 



AND 



E. A. MINCHIN, M.A., 



PROFESSOR OF PROTOZOOLOGY IN THE UNIVERSITY OF LONDON. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGUEES. 



J. & A. CHURCHILL, 



LONDON . 

 7 GREAT MARLBOROUGH STREET. 



1910. 





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