Reviews— E. J. Dunn — Pebbles. 423 



YI. — Pebbles. By E. J. Dunn. 8vo; pp. 122, 76 plates, containing 

 250 figures. Melbourne, etc. : Robertson & Co., 1911. 



SIR ARCHIBALD GEIKIE, in his shilling Primer of Geology, 

 told the story of a Pebble in perhaps the simplest and clearest 

 language that was possible. Mr. Dunn has amplified this story and 

 told us pretty well all that there is to know about the subject. 

 And his many excellent illustrations range from ordinary pebbles in 

 all their stages to wind-worn stones, impressed pebbles, crushed 

 pebbles, obsidian buttons, and ice-scratched stones. His book has 

 nine pages of double-column index and twenty-six pages of description 

 of plates. It is divided into seven chapters, as follows : Miscellaneous, 

 Forms of Pebbles, Material of Pebbles, Eormation of Pebbles, Varieties 

 of Pebbles, Transport of Pebbles, and Uses of Pebbles to Man. 

 Of these chapters we give the heads of chapter iv as illustrative 

 of the treatment: — The Eormation of Pebbles. — Mechanical Agencies : 

 Heat and Cold — Wind — Water — Ice — Volcanic Action — Earth Move- 

 ments. Organic Agencies. Chemical Agencies : Reactions between 

 Rock-forming Minerals — Australites. Plant Agencies. Animal 

 Agencies. 



Among the more curious notes in the book are those on Australites, 

 which he says are often water- worn or wind- worn into true pebbles, 

 although their origin is clearly volcanic ; and the little piles of stones 

 which seem to be properly recognized as gizzard-stones of dead Moas. 

 In this latter connexion the interesting paper by Mr. W. H. Wickes 

 on Stomach Stones, and the more recent note on a find of a pile of 

 stones said to have come from an elephant, would have been too 

 recently published for inclusion in Mr. Dunn's book. We note 

 a certain amount of repetition which Mr. Dunn would do well to avoid 

 in another edition, and the omission of a Bibliography which would 

 have been of great use to those interested in a side issue of this kind. 

 The book is dedicated to Professor J. W. Judd. The price is not 

 stated. 



VII. — The Chief Geological Zones and their Mollusca. By 

 R. Bullen Newton. Being Presidential Address to the Malaco- 

 logical Society, February, 1911. 



THE subject of this address was chosen with a view of placing before 

 the student of recent Mollusca one of the many important 

 applications of the Mollusca found fossil as indexes to the age of the 

 sedimentary rocks and consequent division of those rocks into zones. 

 It is intended as a handy reference paper, includes an abridged table 

 of the stratified rocks, and deals mainly with the Mesozoic beds. 

 The paper is historical in arrangement, and the woi'k of each successive 

 man is easily ascertainable. In his abridged table Mr. Newton gives 

 the chronological terras in general use and the equivalent British 

 formations. As Dr. Marr indicated in his address to the Geological 

 Society (1905), we require three groupings — (1) the formations more 

 or less local, (2) the broad chronological divisions, and (3) the zones. 

 That " Zones are belts of strata, each of which is characterized by an 

 assemblage of organic remains of which one abundant and characteristic 



