516 Revieivs — McKenry and Watts — Bochs and Fossils. 



such use of terms we find the Ordovician sills of Carnarvonshire, 

 the Whin Sill, and the Clee Hill rock named diabases, but when 

 we look for dolerites amongst the volcanic subdivision we find 

 the term not very decisively defined and applied to only two rock- 

 groups, those known as Toadstones in Derbyshire and the ophitic 

 and granulitic rocks of the Inner Hebrides. 



It is interesting to notice that the criterion of age is once and for 

 all swept away in naming volcanic rocks, and the author uses 

 such terms as rhyolite, trachyte, and basalt for volcanic rocks of 

 Tertiary and pre-Tertiary ages. 



Sedimentary rocks are dealt with in considerable detail under 

 the usual headings, and we would call especial attention to the 

 full and accurate treatment of the calcareous division, which includes 

 an account of the microscopic appearance of the chief organic 

 constituents of these rocks. 



The last but by no means least important part of the work is 

 devoted to the consideration of metamorphism, beginning with 

 a masterly account of the minerals developed by thermal action in 

 various kinds of rocks, igneous, sedimentary, and even foliated. 

 Dynamic metamorphism is also ably treated, a distinction being 

 drawn so far as possible between the direct eflfects of pressure and 

 movement and the secondary effects due to heat liberated by crush- 

 ing and shearing. A lumber room has still to be provided for the 

 reception of "various crystalline rocks," including schists, gneisses, 

 granulites, and eclogites ; some of these are shown to be due to 

 thermal metamorphism, others to dynamic action on sedimentary or 

 igneous material, and the rest are probably original igneous products. 



The Pitt Press is to be congratulated on the printing and appear- 

 ance of the book, and the proof-sheets have evidently been read with 

 extreme care ; but it is a great pity that the drawings, on which 

 much labour has clearly been spent, presumably by the author, have 

 not been reproduced by some more satisfactory process, which would 

 have dealt more tenderly with the minuter details in them. 



In closing the book we have only two words to add to the student, 

 be he field-worker, petrologist, or mineralogist — Read it. 



w. w. w. 



IV. — Guide to the Collections op Rooks and Fossils belonging 



TO THE Geological Survey of Ireland. By A. McHenry, 



M.R.I.A., and W. W. Watts, M.A., F.GS. 8vo, pp. 156. 



(Dublin : Printed for Her Majesty's Stationery Office by 



Alexander Thom and Co., 1895. Price 9d.) 



rpHE collections of rocks and fossils belonging to the Geological 



_L Survey of Ii'eland are deposited in the Science and Art Museum 



at Dublin. Commenced when Jukes was Director of that Survey, 



the collections of late years have been much amplified, so that they 



are well calculated to illustrate the general geology of Ireland. The 



original collection was fully described in a catalogue prepared by 



Jukes, and all the facts of importance published therein have been 



incorporated in the present volume. Moreover, the works of the 



