xii INVERTEBRATA 



of the Ctenophora The formation of the tentacles of Callianira The affinities 

 of the Ctenophora with other Coelenterata The experimental embryology of 

 Coelenterata The ancestral meaning of the Planula larva . . Page 53 



CHAPTER V 

 PLATYHELMINTHES 



The Polyclada the most primitive group of Platyhelminthes so far as their develop- 

 ment is concerned Development of Planocera inquilina as a type of the Polyclada 

 The nature of spiral cleavage Definition of cell-lineage and the nomenclature 

 employed Miiller's larva in the development of Yungia and its metamorphosis 

 The interpretation of Miiller's larva and the light which it throws on the 

 ancestral history of Platyhelminthes ..... Page 102 



CHAPTER VI 



NEMERTINEA 



The development of Cerebratulus lactcus as a type of the Nemertiiiea The Pilidium 

 larva and its metamorphosis Experimental embryology of the Nemertinea The 

 interpretation of the Pilidium larva and the light which it throws on the 

 ancestral history of Nemertinea ..... Page 118 



CHAPTER VII 



ANNELIDA 



Methods of preserving and mounting the eggs of Annelida The development of 

 Polygordius appendiculatus as a type of the Annelida: its cell - lineage : its 

 Trochophore larva and the metamorphosis thereof The Trochophore larva of 

 Polygordius lacteus and its metamorphosis The development of various 

 Polychaeta The development of the nephridia of Criodrilus The development 

 of Ncphelis as a type of the Hirudinea The development of Clepsine The inter- 

 pretation of the Trochophore larva and the ancestry of the Annelida . Page 128 



CHAPTER VIII 

 ARTHROPODA 



The development of Peripatus capensis as a type of the Prototracheata The develop- 

 ment of Astacus as a type of the Crustacea The formation of layers in Homarus, 

 Lucifer, and Euphausia as types of the Eucarida The formation of layers in 

 Mysis as a type of the Peracarida The formation of layers in Polyphemus and 

 BrancJiipus as types of the Cladocera The formation of layers in Lepas as a type 

 of the Cirripedia The larval history of Cyclops as a type of Crustacean larval 

 history : the Nauplius and Metanauplius larval stages The larval history of 

 Phyllopoda : the Nauplius larva of Apus and Branchipus The larval history of 

 Cirripedia : the Nauplius and Pupa stages The larval history of Ostracoda 

 The larval history of Euphausidacea and Penaeidea : the Nauplius, Protozoaea, and 



