'A 

 D 



CONTENTS. 



Pago. 



DISTINGUISHING CHARACTERS OF MOLLUSCOUS ANIMALS, 1 



CHAPTER I. 



PHYSIOLOGY. 



1. Structure and appendages of the skin. The formation of 



shells, 3 



2. Muscular system. Modes of rest and motion, 10 



3. Nervous system. The brain. Organs of sense, 12 



4. Digestive system. Phytivorous and carnivorous Mollusca. 



Tentacula. Salivary glands. Stomach and biliary organs, 14 



5. Circulating system. Lungs. Gills, - 17 



6. Peculiar secretions- Colouring matter. Threads. Light. 



Air. Pearls, 19 



7. Generative organs, 19 



8. Condition of the Mollusca. Residence. Torpidity. Qui- 



escence, 20 



CHAPTER II. 



PROGRESS or THE SCIENCE. SYSTEMS OF ARRANGEMENT. 



1. Systems constructed from circumstances connected with the 



characters of the Shell. Aristotle. Linnaeus. Bosc. Writ- 

 ers on microscopic shells, 26 



2. Systems constructed from circumstances connected with the 



Habits of the Animal. Lister. Sibbald. D'Argenville. 

 Schroter ~ 33 



3. Systems constructed from circumstances connected with the 



Form and Structure of the contained animal- Adanson. 

 Muller. Poli. Cuvier, 35 



