1898] SOME NEW BOOKS 279 



named authors whose names give weight to (or, take it away from) 

 their statements ? 



An appendix contains a vahiable list of books and papers bearing 

 upon the county. The vohnne is printed as the (Cambridge Univer- 

 sity Press can print. Errata are very few. It is a book likely to 

 assist geologists, but not likely to create them. We have no right 

 to expect the illumination of genius and we do not find it. Dr 

 Bonney in the preface to his sketch of ' Cambridgeshire Geology,' 

 hoped that it might be superseded by a Geology of the Valley of 

 the Cam, to form a companion to that which Philli[)s executed 

 for Oxford ; and hoped that the present Professor would take it in 

 hand. These hopes are not fulfilled. 



A Student's Petrology 



Petrology for Students. An Introduction to the Study of Rocks under the Micro- 

 scope. By Alfred Marker, M.A., F.G.S. Second edition, pp. viii + 334. 75 

 figures. Cambridge Natural Science Manuals. Cambridge : University Press, 

 1897. Price 7s. 6d. 



The first edition of Mr Marker's " Petrology for Students " took rank 

 as the most practical and best of the elementary English text-books 

 on that science, and as perhaps the most useful students' book in the 

 Cambridge " Natural Science Manuals." The present edition may be 

 expected to be even more useful, for though only 27 pp. longer, 

 it has been extensively revised and considerably improved. The 

 references to foreign rocks especially have been largely increased, 

 which in a general sketch of the subject is a step in the right direc- 

 tion. The author ingeniously overcomes the difficulty of dealing with 

 many rock names, the value of which is doubtful, by not using them 

 in the text, but quoting them in the index with a reference to the 

 page where the rock is described. Thus, for instance, Monchiquite is 

 given in the index with a reference to p. 143, where the rock is 

 described as a type of ultra-basic lamprophyre, but the actual term 

 is not used. The "yogoite" of Weed and Pirsson, the "grorudite" 

 and " akarite " of Brogger, and the " litchfieldite " of Bayley, refer- 

 ences to which are added in this edition, are all thus treated. 



Another improvement is the adoption of the name " Hypabyssal " 

 rocks instead of " Intrusive " rocks for the author's second group, in 

 which are included the acid intrusives, porphyrites, diabases, and 

 lamprophyres ; for there can be no doubt that many of both plutonic 

 and volcanic rocks are sometimes intrusive. 



Northern Spain 



In Northern Spain, By Hans Gadow. 8vo, pp. xvi + 421. London: A. & C. 



Black, 1897. Price 21s, 



In this entertaining volume Dr Gadow has combined a general 

 account of two extended journeys through little known parts of 

 northern Spain, with a valuable synopsis of his observations on the 

 natural history of the country. He also makes special reference at 

 times to practical matters affecting a traveller ; so that his narrative 

 will not only be read with interest by those who are unable to imitate 



