38 Reviews — The British Orthotetince. 



IV. — Causal Geology. By Professor E. H. L. Schwarz, A.lt.C.S., 

 F.G.S. Blakie and Son, Ltd. 



I^HIS work treats of the origin of the earth, of the source of the 

 earth's rocks, the atmosphere and oceans, and of the processes 

 and agents which induce changes on the earth's surface. It may be 

 said to be a vindication and elaboration of the planetismal hypothesis 

 of Chamberlin. The author has evidently given much attention to 

 the problems of causative geology, and, in addition to the results 

 of personal observation, he has collected a formidable array of facts 

 and statistical data as evidence of the various hypotheses he pro- 

 pounds or theories he supports. At the same time, the subject 

 at his hands has received somewhat unequal treatment, and his 

 reasoning is not always easy to follow. 



The book is one which reflects the working of a scientific mind, 

 but it is felt that unconsciously the author has now and then 

 correlated the obvious with the obscure, and placed uncontroverted 

 facts side by side, and on the same plane, with mere conjectures. 

 Some of his deductions thus seem hardly warranted, but apart 

 from the controversial portion of the work, which in itself is of 

 much interest, the book is full of scientific facts and observations 

 from cover to cover. 



It is well printed, and the illustrations, of which there are thirty- 

 two text-figures and. several plates, are exceedingly clear and well 

 reproduced. 



H. H. T. 



V. — The British Carboniferous Orthotetinj5. By Ivor Thomas, 

 B.Sc, Ph.D. Memoirs of the Geological Survey of Great Britain : 

 Palaeontology, Yol. I, Part II, pp. 83-134, and Plate XIII. 4to. 

 London, 1910. Price 2s. 



IN the Geological Magazine for February, 1909 (p. 76), attention 

 was drawn to the publication of Dr. B. N. Peach's Monograph on 

 the Higher Crustacea of the Carboniferous Rocks of Scotland. The 

 present memoir or monograph is paged in continuation of the volume 

 of which that work was the first part. 



The sub-family Orthotetinse belong to the Brachiopod family of 

 Strophonienidse, and the aim of the author is to determine more 

 particularly the British genera and species that belong to the sub- 

 family. The genera now recognized are Mee/cella, Orthotetes, Derbgia, 

 Schellwienella, Schuchertella, Streptorhynchus, and Geyerella, all except 

 the last-named (which is a Permian genus) occurring in British strata. 

 Schellwienella is a new genus now described by the author. The 

 genotype is Spirifera crenistria, Phill., a familiar species, which like 

 many another has passed through various phases of nomenclature, at 

 one time known as Streptorhynchus crenistria, at another as Orthotetes 

 crenistria. The author, however, shows that the form figured by 

 Davidson as Streptorhynchus crenistria is a Schuchertella ; and as he 

 remarks, "It is inevitable that the application of more critical methods 

 and the acquirement of fresh evidence, both morphological and strati- 

 graphical, should lead, from time to time, to revisions of classification 



