New Series, No. 220 (Vol. 55, Part 4). Price 10s. net. 



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



NOVEMBEE, 1910. 



THE 



QUARTERLY JOURNAL 



OF 



MICROSCOPICAL SCIENCE. 



EDITED BY 



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



■IflNOKAUy KKM.OW OK K.XKTKR C UM.KGK . UXFOK I> ; 



MEMBEK OK TUE INSTITUTE Or KIIANCE (ASSOClfi fiTBAKGEK DE i/aCAUEMIE DES SCIENCES) ; 



COH It KSPONltENT OF T II K IMPEKIAI. ACADEMY OF SCIE^CES OP ST. PETEK8BUKG, AM) OF THE 



ACAllKMV IIP 6CIE\CES OF P H I LAUK I.P III A , AMI OF THE BOYAI. ACADEMY OF SCIENCES 



OF TlfRIN; FOUEIGN MEHBBK OF THE UOYAI. SOCIETY OF SCIENCES OF 



GOTTINGEN, AND OF THF, UOYAI, BOHEMIAN SOCIETY OF SCIENCES, AND 



OP THE ACADEMY OP THE I.INCEI OF KOMK, AND OP THE AMEIUCAN 



ACADEMY OF AKTS AND SCIENCES OF B0-J1ON ; ASSOCIATE OF T I! K 



ROYAI. ACADEMY OF BELGIUM; IIONOKAKY MEMERK (iF T U K 



NEW YOKE ACADEMY OF SCIENCES, AND OP THE 



CAMBRIDGE P H I MISOI' H ICAI, SOCIETY, AND OP 



THK UOYAI. PIIYSICAI, SOCIETY OF KDIN- 



B II UGH, AND OF THE 



BIOLOGICAL BOCIKir OF PARIS, AND OF THE CALIFilUNIA ACADEMY OF SCIENCES OF SAN FRANCISCO, AND 



OF THK KOVAL ZOOLOGICAL AND M A LA COLOGIC A L SOCIETY OF BELGIUM; 



CORRESPONDING MEMBER OF THE SENKENBEUG ACADEMY OF FKAN KFUKT-AM J 



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



AMERICAN PHILOSOPHICAL SOCIETY; 



HONORARY FELLOW liF THE ROYAI. SOCIETY OF EDINBURGH; 



LATE DIRECTOR OF THE NATURAL HISTORY DEPARTMENT! OF THE BRITISH MUSEUM; LATE PRESIDENT OF IHE 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE; LATE FUI.I.ERIAN PROFESSOR OF 



PHYSIOLOGY IN THE ROYAL INSTITUTION OF GREAT BRITAIN ; 



LATE LINACRK PROFESSOR OP COMPARATIVE ANATOMY AND FELLOW UP MERTON C OM.K G E , OX F I) B D i 



EMERITUS PROFESSOR OF ZOOLOGY AND COMPARATIVE ANATOMY IN UNIVERSITY COLLEGE, UNIVERSITY OF LONDON. 



WITH TIIK CO-OPKUATION OK 



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



KKM.OW OV THIMTY tUI.I.EaE, C A M B It I DGE . A X D PHOFESSOR OF ZUOLOGY IN THE 1 M P E K I A I. OOM.EGE OF 



SCIENCE AND TECHNOI.OGy, LONDON: 



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



KSSdl', OK ZOliI.oGV l?i THK UNlVEHSITY OF M 



E. A. MINCHIN, M.A., 



BEVKii PliOFESynr. OF ZliIiI.oGV IN THE UNIVERSITY OF M A N C II E.IT K K ; 



FRiiFKSSOR OF PROI OZOOI.OGY IN THE UNIVERSITY OF LONDON; 



AND 



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



I.INACRE PUOKESSOR OF COMPARATIVE ANATOMY, AND FELLOW OF MERTON COILEGK, OXFORD, 



WITH LITHOGRAPHIC PLATES AND TEXT-FIGURES 



L O A' D K . 

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



1910. 



Adlard and Son, Impr.,] 



[London and Dorkine. 



