Diamonds and precious stones, a popular account of gems .. . Fig. 7.—Fossil Dragon-fly of the Secondary Epoch. ever appears, or possibly could appear, in rocks ofthis kind. In sedimentary formations, on the con-trary, such remains abound, and furnish anotherexcellent means of distinguishing them from theigneous rocks. A few illustrations will exemplify types of animaland vegetable fossils incident to different periods. GEOLOGICAL POSITION. II Figs. 4, 5, and 6 represent animal and vegetableforms that existed in a period incalculably remote,. Fig. 8.—Turrilites catenata.

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Keywords: ., bookcentury1800, bookdecade1870, booksubjectgems, booksubjectprec