Revieivs and Book Notices. 519 



tended to avoid controversy. The author accepts Sedg- 

 wick's term Cambrian for the next rocks in succession, 

 calling the Longmynd and Menebian Lower Cambrian, and 

 leaving us to choose whether we shall call the Lingula Flags 

 and Tremadoc Series Middle or Upper Cambrian. So, in like 

 manner, he seems to leave us to choose as to whether the 

 Ordovician Series of Lapworth shall be called Upper Cam- 

 brian or Lower Silurian, or neither. This is no doubt in- 

 tended to conciliate opposing geological factions; but it 

 tends to obscure the grand general fact that the rocks from 

 the Longmynd to the Lower Tremadoc, inclusive, hold what 

 Barrande has called the Primordial fauna, while the rocks 

 from the Arisaig to the top of the Caradoc, hold the Second 

 Palaeozoic fauna. This is the real distinction. Both the 

 Cambrian and the Ordovician vary greatly in mineral 

 character, even within the limits of England, but they 

 differ in their fossil contents just as the latter does from the 

 the proper Silurian above it. 



This leads to the remark that the book is almost 

 entirely stratigraphical, and gives little information as to 

 fossils. There are, it is true, lists of names, but nothing 

 more, and in this respect the work forms a remarkable con- 

 trast to Murchison's Siluria or to Phillip's geology of 

 Oxford. It is in accordance with this neglect of fossils that 

 a little further on we find the term " New Eed Sandstone" 

 retained for the Permian and Trias, and the former asso- 

 ciated with the Mesozoic. It is no doubt sometimes difficult 

 locally to separate them, but the natural arrangement is 

 undoubtedly to place the Permian in the Upper Pakeozoic, 

 and the Trias in the Lower Mesozoic. 



As is natural in the Geology of England, a large propor- 

 tion of the book is devoted to the Mesozoic and older Ter- 

 tiary, and a very clear and connected account of these beds 

 is given. The Pleistocene and its glacial period come in 

 for somewhat extended consideration, and the various com- 

 plexities which they present in England, are freely dis- 

 cussed. He appears to admit the following changes: — 



1. A period of elevated land and cold immediately after the 

 Pliocene (earliest boulder clay). 



2 . A period of submergence (shells — sands of Moel Try phaen, &c). 

 3 • A second period of elevation with glaciers and " variable cli- 



matal conditions, followed by partial submergence. 



4 . Modern conditions with early elevation and subsequent slight 

 depression of land. 



With the exception of a probably exaggerated value 

 attached to No. 1 of the above table, it is hot very remote 

 from the general sequence which we obtain on the wider 

 area of North America. 



