TABLE OF CONTENTS. vii 



CHAPTER XIX. 

 General charactera of the Mollusca— Primary divisions of the Mollusca, . Pages 164^-167 



CHAPTER XX. 



Molluscoida — General charactera of the Polyzoa— General characters of the Tunicata — Gen- 

 eral characters of the Brachiopoda, p. 16S-175 



CHAPTER XXI. 



Classes of the Mollusca Proper — General characters of the LameUibranchiata — General char- 

 acters of the Gasteropoda — ^Nudibranchiata^Heteropoda— Air-breathing G^steropods — 

 Pteropoda, p. 176-186 



CHAPTER XXII. 



General charactera of the Cephalopoda — Reproductive process in the Cuttle-fishes — Shell of 

 the Cephalopoda — Dibranchiata — Tetrabranchiata — Orthocerata — Ammonites— Tabular 

 view of the main divisions of the Mollusca, p. 187-194 



CHAPTER XXIII. 



General characters of the Vertebrata — Skeleton of Vertebrates — Structure of a Vertebra — 

 Vertebral column — Limbs of Vertebrates — ^Digestive system — Circulatory system — Re- 

 spiratory system — ^Nervous system — ^Reproduction — Primary divisions— Ichthyopsida — 

 Sauropsida — Mammalia, p. 195-205 



CHAPTER XXrV. 



General characters of the Fishes— Scales— End oskeletou — Limbs — Tail— Digestive system — 

 Circulation — Respiration — Nervous system — Organs of hearing and smell — Reproduc- 

 tion, p. 206-213 



CHAPTER XXV. 



Orders of Fishes — Pharyngobranchii — ^Marsipobranchii — Teleostei — Sub-orders of the Tele- 

 ostei — Ganoidei — Elasmobranchii — Sub-orders of the Elasmobranchii — Dipnoi, 



p. 214^224 



CHAPTER XXVI. 



General charactera of the Amphibia — Orders of the Amphibia^-Ophiomorpha — Urodela — 

 Anoura — ^Labyrinthodontia, p. 225-233 



CHAPTER XXVII. 



General characters of the Reptilia — Circulatory and Respiratory systems^Divisions, 



p. 234^-237 



CHAPTER XXVin. 



Orders of Reptilia — Chelouia — Ophidia — Lacertilia— Crocodilia — Ichthyopterygia — Saurop- 

 terygia — I*teroaauria, p. 238-252 



CHAPTER XXIX. 



General characters of the Class Aves — Feathers — Vertebral column — Anterior extremity 

 and pectoral arch — ^posterior extremity and pelvic arch — Digestive system — Respira- 



