Book Notices. 499 



Though their affiliations are obscure, the concensus of such high 

 Swedish authorities as those above cited, that the objects are organic, 

 is valuable, as making known a type of pre-Cambrian animal not 

 hitherto recognized. 



The formation, or terrain, in which these fossils are found is described 

 as pre-Cambrian, but nevertheless Palseozoic ; hence it would appear 

 to hold the same relation to the Cambrian of Sweden that the Etchu- 

 ninian series does to that of Canada. 



A plate, with figures and section of the fossil accompanies the 

 article. G. F. M. 



Minerals, and How to Study Them : A Book for Beginners in 

 Mineralogy. — By Edward Salisbury Dana, Yale University, New 

 Haven. John Wiley and Sons, New York, 1895, pp. 380. 



This little book is a most welcome addition to the rather scanty 

 literature of elementary mineralogy, and will, we hope, be widely read 

 not only by " the young people of both sexes," but by many of larger 

 growth. Books on " popular science ;; multiply apace, but while many 

 of them are popular, few are scientific. In Dr. Dana's new volume, 

 however, we have an example of a work which is thoroughly scientific, 

 and which, Ave think, is sure to prove popular. The author himself 

 tells us in the preface that " the attempt has been made to present the 

 whole subject in a clear, simple, and so far as possible a readable form, 

 without too much detail, and at the same time without cheapening the 

 science. " The attempt has been successful. 



As an example of the style in which the book is written, we give 

 the following extract from the introductory chapter : — 



"And here it is important to realize how little we can know by 

 actual contact and direct observation about this earth, though we live 

 upon it. It is possible, indeed, to measure its size and shape, to find 

 out its density as a whole, to study its surface features and the changes 

 which they have undergone ; but of the materials of which it is made 

 we can know little beyond those which form the surface upon which 

 we walk. The miner digs down a little distance, and the artesian- well 

 borer goes down still deeper, and we may have a chance to examine 

 the specimens that their work brings up ; or perhaps we can go down 

 with the miner and see them in place. But the deepest mines descend 

 to less than three-quarters of a mile ; and though this seems deep to 

 one who is let down a shaft in a bucket, it is but a little way compared 

 with the whole distance to the earth's centre, which would require a 

 journey of nearly four thousand miles. Even the deepest artesian-well 



borings hardly go down to the depth of one mile. 



******** 



" Thus the mineralogist is limited to the study of the little part of 

 the crust of the earth which he can reach with his hammer ; and he 



