CONTENTS OF No. 184.-New Series. 



MEMOIRS 



The Movements aud Reactions of Fiesli-water Planariaiis : a Study 

 in Animal Behaviour. By Kaymond Peael, Ph.D., Instructor in 

 Zoology in the Uuiveisity ol' Michigan, Ann Arbor, Michigan, 

 U.S.A 509 



On the Diplochorda. — Part IV. Oa the Central Complex of Cejjhalo- 

 discus dodecalophus, McI. By A. T. Mastemian, M.A., 

 D.Sc, Lecturer on Zoology, School of Medicine, Edinburgh. (With 

 Plates^ 32,"33) 715 



On Hypurgon Skeati, a New Genus and Species of Compound 

 Ascidians. By Igerna B. J. Sollas, B.Sc.Lond. (With Plates 

 ' 34,^35) . " 729 



The Anatomy of A r e n i c o 1 a a s s i mi 1 i s, Ehlers, and of a New Variety 

 of the Species, with some Observations on the Post-larval Stages. 

 By J. H. AsHWoRTH, D.Sc. (With Plates 36,^37) . . .737 



Title, Contents, and Index. 



