., i'ENTS. 



LETTER IV. 



PAGE 



The pearl Oyster, 49 : Pearls, their estimation and value amongst 

 the Romans, 49 — 52 ; ancient Pearl fisheries, 52 : Pearl fishery of 

 Ceylon, 53, 54 : of the Red Sea, 54 : of Britain, 54 — 58 : of America, 

 58 — 62. — Shells worn as ornaments, 62, 63 : economical use of shells, 

 63, 64 : models for utensils and ornaments, 65, 66 : used in religious 

 services, 66, 67 : pilgrim shells, 67, 68.— The Pinna, 68 : its silk, 68, 

 69 : the Tyrian purple, 69—72 : the dye of the Whelk, 72—74 : the 

 Tyrian purple, 74, 75 : China-ink, 76 : Mother-of-pearl, 76, 77 : 

 medicinal Mollusca, 77 : their vulgar uses, 77, 78 : their superstitious 

 applications, 79, 80. ....... 49 



LETTER V. 



The use of the dead shell to other animals, 81 : the Hermit Lobster, 

 82, 83 : the Spider, 83, 84 : the Siphunculus, 84 : insects and worms, 84 : 

 the Nautilus, 84—86. . . . . .81 



LETTER VI. 



The Mollusca in their relations to dead matter : the Teredo, 87 : 

 saxieavous Mollusca, 88, 89 : the origin of lime, 89 — 91 : the creation 

 and succession of the Mollusca, 91 — 94 : tertiary formations, 94 : recent 

 formations, 94 — 96 : checks to the increase of Mollusca, 97 — 98. . 87 



LETTER VII. 



An exposition of Cuvier's arrangement of the Mollusca : the cha- 

 racter of Mollusca, 100, 101 : their classes ; viz., Cephalopods, 101 : 

 Ptcropods, 101 : Gasteropods, 101 : Acephales, 101, 102: Brachiopods, 

 102 : Cephalopods, order and families, 102, 103 : Ptcropods, their 

 genera, 104 : Gasteropods, their orders, 104 : Pulmones, 105 : Nudi- 

 branches, 105 : Inferobranches, 105, 106 : Tcetibranches, 106 : Hetc- 



