The kindness which a traveller receives when in a distant land, must ever be among his most pleasing recollections your attentions therefore to me, during any short residence in London a few years since, cannot easily be forgotten. Suffer me, then, to inscribe this little work to you as a token of my gratitude.
Our pursuits in the Natural and Physical Sciences have been congenial. Your interesting researches with your original and magnificent Galvanic Battery, first drew my attention to the calorific effects of that mysterious agent; and your works on Natural History have stimulated my exertions in the same fascinating pursuit.
A large portion of your time and fortune have been devoted to the patronage or the cultivation of Natural Science so that the dedication of this work to you, if it were infinitely more worthy of your acceptance, would be due from me, both as a tribute of high respect, as well as of grateful acknowledgment.
Philadelphia, October 1st, 1832.
EXPLANATION OF THE PLATE.
| Figure | 1. | Trimerus Delphinocephalus. |
| 2. | Calymene Diops. | |
| 3. | Asaphus Micrurus. | |
| 4. | Cryptolithus Tessellatus. | |
| 5. | Paradoxides Boltoni. | |
| 6. | Triarthrus Beckii. | |
| 7. | Isotelus Cyclops. | |
| 8. | Dipleura Dekayi. | |
| 9. | Head of D. Dekayi. | |
| 10. | Ceraurus Pleurexanthemus. |
The above figures represented on the [Frontispiece] to this volume, were first published in the Monthly Journal of Geology, &c. for June, 1832, and I am indebted to C. A. Poulson, Esq., for the use of them in this Monograph.
INTRODUCTION.
Some geologists imagine that the order of creation is registered in the rocks which compose the external crust of the earth, and that they can there clearly read a progressive development of organic life; in other words, that a succession of more perfect animals may be traced in ascending from the lower strata to the upper or more recent formations; that there is a gradual approach to the present system of things, and a succession of destructions and creations; worlds of living beings alternating with worlds of desolation and death, antecedent to the existence of man.