But man may find in the knowledge of Mollusca applications still more direct to his well being in society, both as to the advantages and disadvantages to be derived from them: thus a great number of species are proper for food, as oysters, mussels, &c., which are objects of commercial speculations. The Pinna furnishes the Italians with materials for a rich dress, and the pearl, so much prized by the Orientals, by princes, and particularly by the ladies, as a modest and beautiful ornament, is produced by a disease of the animals in certain species of shells. It was this knowledge which made the celebrated Linnæus imagine that it was possible to form an artificial pearlery in the rivers of Sweden. The mother of pearl, so much employed as an ornament in articles of luxury, is only the interior lining of certain univalve or bivalve shells. Painting draws from some of these animals many colours, valuable not so much for their beauty as their usefulness, as Chinese ink and sepia. The brightest and richest colour known by the ancients, and used by them for the celebrated Tyrian purple dye, is produced by animals at this time known by the name of Purpura. The Teredo attacks the wood of our vessels, and often does much injury; therefore the knowledge of its manners, habits, and customs must be of great importance in countries infested with them, so as to be able to provide a remedy against them. Snails and slugs are also enemies much to be dreaded in our gardens. Lamarck, in his last work, the result of the successive and continual labours of his whole life and those of his contemporaries, has rendered a very great service to science, but especially to conchology, by describing, or, at least, characterizing the numerous species of shells in his own splendid cabinet. It may be proper here to remark, that a part of Lamarck’s cabinet is now in the possession of Isaac Lea, Esq., of Philadelphia, to whom we are much indebted for valuable assistance. To Dr. Comstock, and the Rev. W. Turner, of Hartford, Conn., we are much indebted for kind favours; their aid has greatly facilitated our labours. In this Manual of Conchology we have endeavoured to give a free translation of Lamarck’s system, as simplified by De Blainville; and, in order to facilitate as much as possible the study of this beautiful and interesting science, we have divested it of numerous technicalities, and divided it into four classes: Annelides, Cirrhipedes, Conchifera, and Mollusca. To each class we have assigned its various families, to each family its genera, and to each genus its living species; thereby making it plain and within the reach of the meanest capacity. A type of almost every genus is given, excepting only those shells which, from their similarity to other genera, may easily be classed.