Contents. 



Preface v 



Chapter 1. Bibliography and General Mor- 

 phology 1 



Review of literature 1 



List of Literature 5 



General Morphology 6 



Relationship of Rhizocephala to other Crustacea 7 



Inter-relationship of the Genera of Rhizocephala 1 2 



Chapter 2. The Sexual Organization of 



the Ehizocephala ■. 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 Sijlon 32 



General discussion 33 



Chapter 3. Embryonic development and 



Larval Stages 39 



Embryonic development of Peltogaster curvatus 



up to Nauplius stage 39 



Larval stages of Peltogaster and Sacculina, in- 

 cluding fixation on host 41 



Chapter 4. The Endoparasitic Development 



of the Ehizocephala 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 Dwplorbis 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- 



achus scorpio 66 



The effect on the primary and secondary sexual 



characters of I. scorpio 66 



Effect on the secondary sexual characters. . . 67 



Effect on the primary sexual character. ... 72 



Crabs of apparently doubtful sex 73 



The Sexual Condition of recovered Crabs ... 74 



The Case of Eriphia spinifrons 76 



The simultaneous parasitism of Entoniscidae and 



Rhizocephala 76 



The nature of the parasitic castration in Eriphia 



spinifrons 50 



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 fixed animals. . . 103 



1 S S"A" 



