xviii GENERAL INDEX. 



CHAPTER IX. 



HOMOGANGLIATA. 



Page Sec. 



HOMOGANGLIATA General type of structure 213 . 555 



Review of the classes composing the Homogangliate division of the 



animal kingdom ,.-.... . 214 . 557 



Arrangement of the nervous system ..,,,* 215 . 562 



CHAPTER X. 



ANNELIDA. 



ANNELIDA General characters of the class 216 



ABEANCHIATA 217 



Anatomy of the Leech (Hirudo medicinalis) . . . . + , :. , . 217 



Structure of muscular integument 217 



Locomotive apparatus 218 



Structure of the mouth 218 



Mechanism of dental saws . . . . , 218 



Internal digestive apparatus 219 



Structure of alimentary canal 219 



Respiratory and circulatory systems of the Leech 220 



Nervous system of the Leech 224 



Splanchnic gangl ionic nerves of Leech 225 



Senses of the Leech 225 



Organs of vision 225 



Hermaphrodite condition of the generative system 225 



Arrangement of male apparatus 225 



Structure of female organs of generation as heretofore described . 226 



Generative system of the Leech, as deciphered by Dr. Williams . 227 



ABRANCHIA TERRICOLA 228 



Anatomy of the Earthworm (Lumbricus terrestris) 228 



Locomotive apparatus 229 



Alimentary system 230 



Arrangement of the circulation 231 



Generative system of the Earthworm 233 



, according to Duges 234 



Dr. Williams 235 



Evolution of ova 238 



Development of embryo 238 



Anatomy of Nais filiformis 240 



Circulatory system of Nais 240 



Generative system of Nais, after Duges 241 



- Dr. Williams 242 



Reproduction by spontaneous division 244 



DORSIBRANCHIATA 245 



Arrangement of respiratory apparatus 245 



Cirri 246 



Seta 246 



Structure of the mouth in the Dorsibranchiata 246 



Goniada 246 



_ .- Amphinome 247 



PhyUodvee 248 



Laodicea 248 



Alimentary canal of the Dorsibranchiate Annelida . . * -., -,.- . 248 



Mechanism of alimentation 248 



Circulatory system of the Dorsibranchiata . 249 



Amphinome 249 



in Eunice mnguinea 250 



Multiplication by gemmation 253 



Respiratory apparatus of Arenicola 255 



