CONTENTS 



Introduction 651 



Material and Records 652 



The Specimens and Their Source 653 



Authorship of the Drawings 655 



Written Records Left by Bashford Dean ; 656 



Classification and Synonymy 657 



Heterodontus and Heterodontidae 657 



Synonymy 658 



Common Names — Bullhead Sharks 660 



Family and Generic Characters 661 



The Species of Heterodontus 663 



Heterodontus pMlipi Blainville 664 



Heterodontus zebra Gray , . . . 675 



Heterodontus quo)ii Freminville 676 



Heterodontus francisci Girard 6ol 



Comparison of H. quoyi and H. francisci 684 



Hetaodontus galeatus Gunther 686 



Heterodontus japonicus Macleay 688 



Affinities to Fossil Forms 694 



Sexual Dimorphism and the Reproductive Organs 702 



The Egg Capsule: Its Structure and Functions 705 



Habits of Heterodontus 709 



Habitat and General Habits 709 



Food and Feeding Habits 710 



Breeding Season 711 



Egg-Laying Habits; The Nests 712 



Methods of Collecting Eggs and Embryos 7i6 



Embryonic Development of Heterodontus japonicus 7i7 



Rate of Embryonic Development 717 



General Mode of Development 722 



The Egg and Its Membranes 723 



Reminiscence of Total Cleavage 724 



Discoidal Cleavage and the Blastula 728 



Gastrulation and Early Embryogeny 732 



The Yolk Blastopore 738 



Later Embryonic Development 740 



The Vitelline Circulation 748 



Hatching and the Newly Hatched Young 752 



A 280'MM. Young Heterodontus japonicus 757 



External and Internal Gill Filaments 758 



Development of the Teeth 760 



Bibliography 764 



649 



