New Series, No. 222 (Vol. 56, Part 2). Price lOs. net. 



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

 FEBEUARY, 1911. 



THK 



QUAUTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



KDITH,)) hV 



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



HONOKAKT i'BI.I.OW OK KXETKK C O I.J.RG B , OX CORD ; 



MEMBER OP THR ISSTITUTB OV KKANCB (aSSUCI£ £tB ANGER DE L'aC.\DEMIE DE3 SCIEXCES) ; 



CURRRSPUKUBKT OP THB IMPKRIAl. ACADKMT OK SCIKXCES Of ST. PETKRBBUKG, A N O OP TUB 



ACADKMY <tP SCIBNCKS OP P II II.A UKI.PII I A , AND OF THE ROYAL ACADEMY OF SCIENCES 



OF Turin; pobkign mkmbkr op tub royal society op sciences of 



GOTTINGEN, AND OF THE ROYAL BOHEMIAN SOCIETY OP SCIENCES, AND 

 OF THE ACADEMY OF THB LINCEI OF KOMK, AND OF TUB AMEBICAN 

 ACADEMY OF ARTS AND SCIENCES OP B0<T0N; ASSOCIATE OK THE 

 BOYAL ACADEMY OK BELGIUM; HONORARY MEMBER oK THE 

 NEW YORK ACADEMY OF SCIENCES, AND OP THR 

 CAMBRIDGE P It I LOS U P U ICAL SOCIETY, AND OF 

 THE ROYAL PHYSICAL SOCIETY OF EDIN- 

 BURGH, AND OF THE 

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

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

 CORRESPONDING 3IEMBER OF THE 8ENKKNBERG ACADEMY OF PR ANKFURT A'M ; 

 FOREIGN ASSOCIATE OF TUB NATIONAL ACADEMY OF SCIENCES. U.S., AND ME5IBER OF THE 

 AMERICAN PHILOSOPHICAL SOCIETY ^ 

 HONORARY FELLOW OF THE ROYAL SOCIETY OF EDINBURGH". 

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

 BRITISH ASSOCIATION FOR THE ADVANCEMENT OP SCIENCK." LaTE Klt|.I.KKIA> PROKRNSOR OK 

 PII VSIOLOGY IN Til K ROYAL I N 3TI T UTI <> N OK « B H AT O R IT A T N . 

 LATE MNACRR PROFESSOR OP COMPARATIVE ANATOMY AND FELLOW OF MEBTON CO LLRG E, nX FO B D ; 

 EMERITUS PB0FES80B OF ZOOLOGY AND C03IPABATIVE ANATOMY IN UNIVERSITY COLLEGE, UNIVERSITY OF LONDON 



WITH THE CO-OPERATION OP 



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



! FELLOW OF TBIMIY COLLEGE, fAMBRIDGE. A>D PROrESSOR OF ZOOLOGY IS THE IMPERIAL COLLEGE OF 



SCIE.XCE AND TECUSOLOGf, LOXDOX; 



SYDNEY J. HIC::SON, M.A., F.R.S., 



BF.VFR PROF1 -SSOK OF Eolil.oGr IX THE UXITERSITY OF M A N f H EST K R ; 



E. A. MINCHIN, M.A., 



PROFESSOR OF PROTOZOOLOGY IN THE UMVEBSITY OK LONDON; 



AND 



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



LIN4CRE PROFFRSIPR OF COMPARATIVR ANATOMY, AXD FKLLOW OF MERTON COLLEGE, OXFORD. 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES. 



L O ^' D N . 

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



1911. 



^t 



Adlard and Son, Impr.,] [I'Onuon and Dorkm;;. 



