3/6 THE POPULAR SCIENCE MONTHLY. 



this department of oui* subject I have ah-eacly laid before you on a 

 previous occasion, and hence need not dwell upon them here. 



In this rapid sketch of the history of paleontology I have thought 

 it best to speak of the earlier periods more in detail, as they are less 

 generally known, and especially as they indicate the growth of the sci- 

 ence, and the obstacles it had to surmount. With the present work in 

 paleontology, moreover, you are all more or less familiar, as the results 

 are now part of the current literature. To assign every important dis- 

 covery to its author would have led me far beyond my present plan. 

 I have only endeavored to indicate the growth of the science by citing 

 the more prominent works that mark its progress, or illustrate the 

 prevailing opinions and state of knowledge at the time they were 

 written. 



In considering what has been accomplished, directly or indirectly, 

 it is well to bear in mind that without paleontology there would have 

 been no science of geology. The latter science originated from the 

 study of fossils, and not the reverse, as generally supposed. Paleon- 

 tology, therefore, is not a mere branch of geology, but the foundation 

 on which that science mainly rests. This fact is a sufficient excuse, 

 if one were wanting, for noting the early opinions in regard to the 

 changes of the earth's surface, as these changes were first studied to 

 explain the position of fossils. The investigation of the latter first 

 led to theories of the earth's formation, and thus to geology. When 

 speculation replaced observation, fossils were discarded, and for a 

 time the mineral characters of strata were thought to be the key to 

 their position and age. For some time after this, geologists, as we 

 have seen, apologized for using fossils to determine formations, but 

 for the last half century their value for this purpose has been fully rec- 

 ognized. 



The services which paleontology has rendered to botany and zool- 

 ogy are less easy to estimate, but are very extensive. The classifica- 

 tion of these sciences has been rendered much more complete by the 

 intercalation of many intermediate forms. The probable origin of 

 various living species has been indicated by the genealogies suggested 

 by extinct types ; while our knowledge of the geographical distribu- 

 tion of animals and plants at the present day has been greatly im- 

 proved by the facts brought out in regard to the former disti-ibution 

 of life on the globe. 



Among the vast number of new species which have been added are 

 the representatives of a number of new orders entirely unknown among 

 living forms. The distribution of these extinct orders among the 

 different classes is interesting, as they are mainly confined to the 

 higher gi'oups. Among the fossil plants no new orders have yet been 

 found. There are none known among the Protozoa or the Mollusca. 

 The Radiates have been enriched by the extinct orders of Blastoidea, 



