VI 



TABLE OF CONTENTS. 



1876 

 IX. On the spinal nerves of Amphioxus . 



187678 



X. A Monograph on the development of Elasmobranch 

 Fishes. With Plates 621 



PAGE 



197 



2O3 



1878 



XI. On the phenomena accompanying the maturation and 



impregnation of the ovum ...... 521 



XII. On the structure and development of the vertebrate ovary. 



With Plates 24, 25, 26 549 



1879 



XIII. On the existence of a Head-kidney in the Embryo Chick, 



and on certain points in the development of the 

 Miillerian duct. By F. M. BALFOUR and A. SEDGWICK. 

 With Plates 27 and 28 618 



XIV. On the early development of the Lacertilia, together with 



some observations on the nature and relations of the 

 primitive Streak. With Plate 29 .... 644 



XV. On certain points in the Anatomy of Peripatus Capensis . 657 



XVI. On the morphology and systematic position of the 



Spongida ' 661 



1880 



XVII. Notes on the development of the Araneina. With Plates 



30, 31, 32 . 668 



XVIII. On the spinal nerves of Amphioxus 696 



XIX. Address to the Department of Anatomy and Physiology 

 of the British Association for the Advancement of 

 Science 698 



1881 



XX. On the development of the skeleton of the paired fins of 

 Elasmobranchii, considered in relation to its bearings 

 on the nature of the limbs of the Vertebrata. With 

 Plate 33 . . 714 



XXI. On the evolution of the Placenta, and on the possibility of 

 employing the characters of the Placenta in the classi- 

 fication of the Mammalia 734 



