^5-^^ 



New Series, No. 202 (Vol. 51, Part 2). Price 10s. net. 



Subscription per volume (of 4 parts) 40s. net. 



MAY, 1907. 



THE 



QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



KUITMI HY 



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



MU^UKAKY FBI. LOW OK EXKTEU C U M. K G K , O X I- O U U ; C Oil K KS T O N D E N T OK THE IXSTITUTK OF KRANCE 

 AND OF TUB IMPKKIAI. ACADEMY OF SCIENCES OF ST. PETKKSBURG, AND OK THE ACADEMY 

 OF SCIENCES OF PillLAUKI-PlllA, AND OF THE ROYAI. ACADF.MY OF SCIENCES 

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

 GOTTINGEX, AND OF THE ROYAL BOHEMIAN SOCIETY OF SCIENCES, AND 

 OF THE ACAItEMY OK THE LINCEI OF ROME, AND OF TUR AMERICAS 

 ACADE.MY OF ARTS AND SCIENCES OK BOSTON; ASSOCIATE OK THE 

 ROYAL ACADEMY OK BELGIUM; HONORARY MEMBER oF THE 

 NEW YORK ACADEMY OF SCIENCES, AND OF THE 

 CAMBRIDGE PHILOSOPHICAL SOCIETY, AND OP 

 THE HOYAL PHYSICAL SOCIETY OK EDIN- 

 BURGH, AND OF THE 

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

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

 THE AMERICAN PHILOSOPHICAL SOCIETY ; 

 DIUECTOK(»F THE NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM; PRESIDENT OF THE BRITISH 

 ASSOCIATION FOR THE ADVANCEMENT OF SCIENCF; LATE KUM.KKIAN PHOFKSSOR OK 

 PHYSIOLOGY IN THE ROYAL INSTITUTION OP GREAT BRITAIN ; 

 LATE LINACRE PROFESSOR OF COMPARATIVE ANATOMY AND FELLOW OF MERTON COLLEGE, OXFORD. 



WITH THE CO-OPKUATION OF 



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



FELLOW AND TUTOR OK TRINITY COLLEGE, CAMBRIDGE; 



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



BEYER PROFESSOR OF ZOOLOGY IN THE OWENS COLLEGE, MAN C HEST K R i 



AND 



E. A. MINCHIN, M.A., 



PROFESSOR OF PROTOZOOLOGY IN THE UNIVERSITY OF LONDON. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES. 



LONDON: 



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



1907. 



Adlard and Son, Impr.,] 



[London and Dorking 



