PREFACE. WITH much of that which is called "Popular Science" the writer of these pages has no sympathy. To read from pages addressed to the memory only, that the sun is so many miles from the earth, is so many miles in diameter, and is enveloped in "whirlwinds of tempestuous fire" so fierce that if they could blow upon the earth they would reduce it in a few seconds to a mist of atoms, may help the mind to astronomical facts and set it aglow with wonder, but it does not teach it astronomy. To read in similar manner that rocks were formed so, or so; that oceans came to be in this wise or that wise; that continents rose through the play of these forces, or those; that life began in one form or in another, and to read how it unfolded and branched from order to order, may be entertaining, but it may have little to do with geology. Facts do not enlarge the mind unless they are fertilized by principles. Our aim in the preparation of this volume has been to conduct the reader through methods to results. The leading types of life which have possessed the earth from age to age he will find described and delineated. He will find the more significant types reconstructed, part by part, with so little of the phraseology of comparative anatomy, that his mind, it is hoped, will traverse the methods and make them its own. To all who have labored in the quarry, the museum, the laboratory, or the library, and who are known to him by their works, the writer acknowledges his indebtedness. Waltham, Mass., Oct., 1876. W. D. GUNNING. વ્યાસ, 2 a Bird ON THE WAY TO A BIRD.-1, A Dinosaur of the Jurassic Period except in teeth, fore limbs and tail. 2 A Bird which lived in Kansas during the Cretaceous Period a Bird in all except teeth, which lingered as vestiges of the Reptile. |