iv CONTENTS. 
4. Mixed Systems, Taiiwk, oo chynuessusinnebdatanianawns toa eeueenocemis 42 
5. Value of the characters employed. Valves of the shell. 
Canaliculated, dextral, operculated, pillared, multilocular, 
free, gaping, equivalve shells. Muscular impressions. 
Marginal impression. Ligament. Teeth. Borers,...... £ 
6. Review of the Linnzan genera,.........0+00 ian ceeapiananaaespaeaers 
CHAPTER III. 
SYSTEMATICAL DISTRIBUTION OF THE MOLLUuUSCA. 
I. Mollusca Cephala. 
1, Natantia. Cephalopoda. Cuttle Fish. Nautilacea. Se- 
piacea. Pteropoda. Limacina. Clid,.......++ waswdesse 119 
2. Gasteropoda. Pulmonifera. Terrestrial. Aquatic.— 
Branchifera. Branchie external. Branchie internal, 144 
II. Mollusea Acephala. 
1. Conchifera. Brachiopoda. Lingula. Terebratula. Bi- 
valvia. Pectenide. Ostreada. Mytilida, .+++1.++++0+++ 186 
2. Tunicata. Dichitonida. Ascidia. Pyrosoma. Mo- 
Nochitonida. Salpa,e.......-ccccoccccrsccecsccscesccseveeseee 19S 
CHAPTER IV. 
Mo.tuvuscous ANIMALS As OxssEcTs oF UTILITY. 
1. Employed as Food. Oyster. Mussel. Cockle. Pearl. Dye, 217 
2. Objects of Beauty. Sane of Shells. Arrangement 
in a Cabinet,.......0.. daisies dines pion was dale ane shevaewanvsteneene enEen 
3. Mode of Be aati ‘Shells. fit Mie kfdsks wiles age daescapnaiee Cateee 233 
4. Fossil Shells. Their systematical, chemical, geognostic, and 
geographical history, o....coccsseseseceescessenseenesesteaneessesens LOO 
