II. AMPHIOXUS AND THE ANCESTRY 

 OF THE VERTEBRATES. 



BY 



ARTHUR WILLEY, B.Sc. Lond., 



Tutor in Biology, Columbia Unirernity ; Tiitlfnur Student of the 

 University of Cambridge. 



8vo. Cloth. $2.50, net. 



The purpose of this vohime is to consider the proldom of tlio 

 ancestry of the Vertebrates from the stan(l})oint of the anat- 

 omy and development of Amphioxns and other members of the 

 group Protochordata. The work opens with an Introduction, 

 in which is given a brief historical sketch of the speculations 

 of the celebrated anatomists and embryologists, from Kticnne 

 Geoffroy St. Hilaire down to our own day, upon tliis ])n)ljK'm. 

 The remainder of the first and the whole of tlie second cliajticr 

 is devoted to a detailed account of tlie anatomy of Am})hi(>xus 

 as compared with that of higher Vertebrates. The tliird chajiUT 

 deals with the embryonic and larval development of Am]»hi<»\iis, 

 while the fourth deals more brietiv with the anatom v, embrvoloirv, 

 and relationships of the Ascidians; then the other allied forms, 

 Balanoglossus, Cephalodiscus, are described. 



The work concludes with a series of discussions toncli- 

 ing the problem proposed in the Introduction, in which it is 

 attempted to define certain general principles of Evolution by 

 which the descent of the Vertebrates from Invertebrate ancestors 

 may be supposed to have taken place. 



The work contains an extensive bibliography, full notes, and 

 135 illustrations. 



TABLE OF CONTENTS. 



Introduction". 



Chapter I. Anatomy of Amphioxus. 

 II. Ditto. 



III. Development of Ampiiioxus. 



IV. The Ascidians. 



V. The Protochordata in their Relation to 

 THE Problem of Vertehrate Desc-ent. 



