76 Revieics — ZitteVs Century of Geology, etc. 



that liis merit chiefly rests on his achievements in vertebrate 

 palaeontology, in establishing a scientific method in the nomen- 

 clature of fossil osteology, and in the convincing proof which he 

 gave that fossil mammals belonged to extinct genera and species 

 and that they could not be regarded as mere varieties of forms now 

 living. At the same time he maintained the unchangeableness of 

 species, and denied that there was any genetic connection between 

 the earlier forms of organic life and the present ones. It must be 

 confessed that on some points he stood at a lower level of knowledge 

 than his contemporaries, and that some of his theoretical conclusions 

 tended to hinder rather than forward the advance of geology. 



The author's fourth period — the more recent development of 

 geology and paleeontology, from 1820 to the present time — is treated 

 at great length, and occupies about three-fourths of the volume. 

 After the close of the last epoch, which might well be termed the 

 spring-time of the science, geology entered on a new phase. Its 

 position as not the least important of the natural sciences had been 

 established, and in most of the great centres of academical leai'ning 

 courses of study were founded and collections of rocks and fossils 

 made for teaching its principles. The pei'iod for gi-eat discoveries 

 had passed ; hasty and superfi.cial observations and wide generaliza- 

 tions were replaced by deeper and more detailed investigation, less 

 brilliant perhaps, but more permanent in its results. The list of 

 eminent professors and teachers of geology in the Universities of 

 Germany during this recent period indicates the high importance 

 attached to the science in that country, in a measure greater than 

 that shown in the corresponding institutions in England and in 

 France. 



The value of geology in many departments of practical life, such 

 as mining, agriculture, building, etc., was not long hidden from 

 Government authorities, and led to the establishment of official 

 Geological Surveys for the purpose of investigating and mapping 

 the geological structure of their respective countries. The first to 

 be founded was that of the Geological Survey of the United Kingdom 

 in 1835, and since then Government Surveys with a similar object 

 have been formed in nearly every State in the civilized world. 

 A further notable impulse to the study of geology in recent times 

 has been derived from the societies and associations for the 

 encouragement of independent researches in the science which have 

 sprung up in different countries. 



The wide field for observation presented by the diverse aspects 

 of geology in its later developments, and the vast store of materials 

 collected from so many varied sources, naturally led to a division of 

 labour amongst the workers, and hence the science became divided 

 up into a series of special depai-tments, more or less intimately 

 linked to each other and to the sister sciences, though often differing 

 materially from each other in their mode of working. It was there- 

 fore impossible to treat the recent development of geology as a whole, 

 and the author has consequently given us a history of the origin, the 

 growth, and the present position of each of the separate branches of 



