CONTENTS OF No. CXXIII.—New Series. 
MEMOIRS: 
On the Origin of Vertebrates from Arachnids. By Witt1am Patten, 
Ph.D., Professor of Biology in the University of North mes 
Grand Forks. (With Plates XXIII and XXIV) 
On the Origin of Vertebrates from a Crustacean-like Ancestor. By 
W. H. Gasket, M.D., F.RS. Shge Plates XXV, XXVI, XXVII, 
XXVIII) 
The Development of the Atrial Chamber of Amphioxus. By 
E. Ray Langester, M.A., LL.D., F.R.S., and ArtHuR WILLEY, 
Student of oa ea (With Plates XXIX, XXX, XXXI,_ 
XXXII) 
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