Contents. 



pag. 



Preface v 



Chapter 1. Bibliography and General Mor- 



phology i 



Eeview of literature 1 



List of Literature 5 



General Morphology 6 



Eelationship of Khizocephala to other Crustacea 7 



Inter-relationship of the Genera of Rhizocephala 12 



Chapter 2. The Sexnal Organization of 



the Rhizocephala 19 



Introduction 19 



The Testes of the Hermaphrodites 21 



The moulting of the mantle-cavity and of the 

 vas deferens and the passage of the ova 



into the mantle-cavity 24 



The maturation and fertilization of the ova . . 27 



The complemental males 29 



The sexual nature of Sylon 32 



General discussion 33 



Chapter 3. Embryonie deyelopment and 



Larvai Stages 39 



Embryonie deyelopment of Peltogaster curvatus 



up to Nauplius stage 39 



Larvai stages of Peltogaster and Sacculina, in- 



cluding fìxation on host 41 



Chapter 4. The Endoparasitic Deyelopment 



of the Rhizocephala 45 



Introduction 45 



Sacculina interna migrans 47 



Sacculina interna. Organogeny and Evagination 49 



Orientation of the body during Organogeny. . 52 



pag. 



The Endoparasitic development of Peltogaster 



curvatus 54 



The Endoparasitic Development of Peltogaster 



socialis, and Polyembryony in Sacculina . . 57 



The general nature of the Endoparasitic deve- 

 lopment of the Rhizocephala 58 



The Morphology of Duplorbis and the derivation 



of the Endoparasitic development 60 



Chapter 5. The effect of the Parasites on 



their Hosts 65 



The general effect of Sacculina neglecta on In- 



aclius scorpio 66 



The effect on the primary and secondary sexual 



characters of /. scorpio 66 



Effect on the secondary sexual characters. . . 67 



Effect on the primary sexual character. ... 72 



Crabs of apparently doubtful sex 73 



The Sexual Oondition of recovered Crabs ... 74 



The Case of Eriphia spìnifrons 76 



The simultaneous parasitism of Entoniscidae and 



Rhizocephala 76 



The nature of the parasitic castration in Eriphia 



spìnifrons v 80 



The Case of Pachygrapsus marmoratus .... 80 



General conclusions and summaries 82 



Special reference of the phenomena of Parasitic 



Castration to High and Low Dimorphism . . 90 

 Correlation tables for ascertaining the effect of 



Sacculina on Inachus scorpio 95 



Chapter 6. Parasites of the Parasites . . 99 



Introduction 99 



The Life-history of Danalia curvata 101 



On the Hermaphroditism of fìxed animals. . . 103 



