522 Revieics — Gosselet's Geological Slictch of North of France. 



of refi-action, for at the summit we leave one-third of the atmosphere 

 beneath us, and in looking towards the base we are looking from 

 a rarer to a denser medium. In a chapter he gives an account of 

 seventj'^-eight eruptions of the volcano. The coloured map of Etna 

 is curioxis in that the beds of modern lava bear the closest resem- 

 blance to stag's horn moss. Mr. Rutley discourses on the microscopic 

 characters of the sections of the lavas, and speaks of " a slight 

 residuum of glass," "some interstitial glass," "a small quantity of 

 intei'stitial glass." Would it not be well to let the reader know 

 what is meant by the very technical use of this word "glass " ? 



III. — Geological Sketch of the North of Fkance and the 

 Adjacent Districts. 



EsQUissE Geologique dd Nord de la France et des Con- 

 trees voisiNKS. Par M. J. Gosselet, Professeur a la Faculte 

 des Sciences de Lille. 2^ Fascicule, Terrains Secondaires. 

 (Lille, 1881.) 



MONG his numerous contributions to geological science, Prof. 

 J. Gosselet has prepared a geological sketch of the Depart- 

 ment of the North and adjacent districts, of which two parts have 

 appeared. A work by him under a similar title, but on a smaller 

 scale, and without illustrations, was published about five years ago. 



The first part of the enlarged edition comprises the Palaeozoic 

 rocks, the present part is devoted to the " Terrains Secondaires," 

 including the Triassic, Jurassic, and Cretaceous series of the 

 northern region of France. The palESontological, mineralogical, and 

 stratigraphical characters of each great division, and their geographi- 

 cal distribution, are given, followed by a concise description of the 

 subdivisions of each group, with lists of the most characteristic 

 fossils, and useful synoptical tables of the Jurassic and Cretaceous 

 strata. This second fasciculus is accompanied by an atlas containing 

 thirteen carefully executed plates of the more characteristic fossils of 

 each subdivision from the Hettangien to the Turonien, four double 

 plates showing the area of the continental land, and of the sea 

 deposits of the Jurassic, Albien, Cenomanien, Turonien, and Senonien 

 epochs, as well as six double plates illustrating fifty-five of the 

 more important geological sections and superposition of the strata in 

 the country. This work when completed will form a useful resume 

 to those interested in the leading geological features of the northern 

 district of France, or in comparing them with the synchronous 

 deposits of our own country. 



For the " Esquisse Geologique " and other memoirs bearing on 

 the geological constitution of the Ardennes, the Academy of Sciences 

 of Paris this year awarded the Bourdin prize, — a worthy recognition 

 of the conscientious labours of Prof. J. Gosselet for many years on 

 the geology of his Department (du Nord) and the adjacent country. 



J. M. 



