XXII. ON THE STRUCTURE AND DEVELOPMENT OF LEPI- 

 DOSTEUS 1 . By F. M. BALFOUR and W. N. PARKER. 



(With Plates 3442.) 

 TABLE OF CONTENTS. 



PAGE 



INTRODUCTION 739 



GENERAL DEVELOPMENT 740 



BRAIN 



Adult brain ........... 759 



Development of the brain 764 



Comparison of the larval and adult brain of Lepidosteiis, together with 

 some observations on the systematic value of the characters of the 



Ganoid brain 767 



SENSE ORGANS 



Olfactory organ 771 



Anatomy of the eye ib. 



Development of the eye 772 



SUCTORIAL Disc 774 



MUSCULAR SYSTEM 775 



SKELETON 



Vertebral column and ribs of the adult ...... 776 



Development of the vertebral column and ribs 778 



Comparison of the vertebral column of Lepidosteus with that of other 



forms 792 



The ribs of Fishes 793 



The skeleton of the ventral lobe of the tail fin, and its bearing on the 



nature of the tail fin of the various types of Pisces . . . 80 1 



EXCRETORY AND GENERATIVE ORGANS 



Anatomy of the excretory and generative organs of the female . . 810 



Anatomy of the excretory and generative organs of the male . . 813 



Development of the excretory and generative organs . . . . 815 



Theoretical considerations 822 



1 From the Philosophical Transactions of the Royal Society, 1882. 



