II. AMPHIOXUS AND THE ANCESTRY 

 OF THE VERTEBRATES. 



BY 



ARTHUR WILLEY, B.Sc. LOND., 



Tutor in Biology, Columbia Fnirersit;/ : Balfour Student of th* 

 Unirernity of Cambridge. 



8vo. Cloth. $2.50, net. 



The purpose of this vohime is to consider tlie proV)h^ni of tlie 

 ancestry of the Vertebrates from the stand i)oint of the anat- 

 omy and development of Ampliioxns and other members of the 

 group Protochordata. The work opens with an Introchiction, 

 in which is given a brief historical sketch of the sj)ecii hit ions 

 of the celebrated anatomists and embryologists, from Ktionnc 

 Geoffroy St. Hilaire down to our own day, upon this problem. 

 The remainder of the first and the whole of tlie second cliai»ter 

 is devoted to a detailed account of the anatomy of Ampiiioxus 

 as compared with that of higher Vertebrates. The third chapter 

 deals with the embrvonic and larval development of Am}>hioxu8, 

 while the fourth deals more briefly with the anatomy, embryoloiry, 

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

 Balanoglossus, Cephalodiscus, are described. 



The work concludes with a series of di.<cussions touch- 

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

 attempted to define certain general in-inciplcs of Kvolution by 

 which the descent of the Vertebrates from Invertebrate ancestors 

 may be supposed to have taken i)lacc. 



The work contains an extensive bibliography, full notes, and 

 135 illustrations. 



TABLE OF CONTENTS. 



Introduction. 



Chapter I. Anatomy of Ami'Iiioxus. 

 II. Ditto. 



III. Development of Ami'Iiioxu^;. 



IV. The Ascidians. 



V. The Protochordata in' Tin:ii: Ixklation t<> 

 the Prorlem or Vkktkhkati: Descent. 



