528 Revieivs — Geology of An-SJian Iron Mine District. 



the organism thereto. Such, adaptation leads to specialization, and 

 specialization hinders survival when conditions change. It is the 

 simple primitive forms that persist and attain the widest distribution. 

 Age and Area, Size and Space, Eank and Eange, and the other artful 

 ;alliterations not only are consistent with these facts, but are, as 

 Darwin showed {Origin, ed. vi, pp. 358-62), their natural corollary. 



This review has dealt with one of the chief points raised by 

 Dr. Willis, one that is of particular interest to geologists and 

 palaeontologists. There are others that one would like to discuss, 

 but it must suffice to say that those who have leisure and 

 perseverance to grapple with a complicated style will find " Age and 

 Area " a stimulating as well as a provocative book. If it do no more 

 than lead them to le-peruse Lyell and Darwin, it will have served a 

 good purpose. 



F. A. Bather. 



Oeology op the An-Shan Iron Mine District, South Manchuria. 

 By H. Murakami, pp. 53, with xxvi plates, 6 text-figures, and 

 a coloured geological map. Published by the South Manchuria 

 Railway Company, 1921. 

 rpiIE important iron-ore deposit of An-Shan, now worked on an 

 -*- extensive scale and smelted locally in two blast-furnaces, lies 

 about 56 miles south of Mukden. The formations found in the district 

 comprise only Pre-Cambrian, Cambrian, and Quaternary sediments, 

 with intrusive igneous rocks. The general geology, as well as the 

 character of the ores, show analogies to the Lake Superior district. 

 The Pre-Cambrian formations are divided by the author into two 

 groups, the Green Schist complex and the Hematite-quartz-schist. 

 The latter differs mainly from the taconite series of Michigan in the 

 fact that the siliceous layers consist of coarsely crystalline quartz 

 instead of chert. The iron ore is locally enriched to a high-grade 

 product, but it is now found necessary to concentrate the leaner ores 

 in order to supply the furnaces. 



The Cambrian rocks include a basal conglomerate, overlain by 

 quartzites, often ferruginous, and siliceous slates ; the Hsiao-fang- 

 shen series at the top includes limestones, and contains Lingulella, 

 Oholus, Acrothele, and the trilobites Agnostus, Ptychoparia, Lisania, 

 Crejpicej)halus, Asaphiscus, and Redlichia. From a comparison with 

 more complete faunas in other parts of Manchuria, these appear to 

 indicate a Middle Cambrian age. The igneous rocks, which include 

 both foliated and unfobated granites, appear to be of no particular 

 interest. 



