Geology and Mineralogy. 129 



plished chiefly in Germany. In California the problems occa- 

 sioned by the overloading of certain rivers with waste from 

 placer mines had become of great economic importance and justi- 

 fied on that basis a thorough study. Thirty-five to forty years 

 ago G. K. Gilbert began to make effective studies in the west on 

 the work of streams in shaping the face of the land, and in their 

 manner of transporting material. These studies, with those made 

 by Powell and Dutton, became the foundation of the modern 

 science of physiography. It was fitting that the same veteran 

 investigator should continue work in this field by taking up this 

 problem of the transportation of debris by running water. His 

 former studies were based upon the results accomplished by 

 nature ; these are based upon experiments made by man. The 

 latter work shows the same thoroughness, perception, and judicial 

 qualities as the former. 



An abstract, pages 10 to 12, gives a summary of the results, so 

 that but little need be said here in that line. The results of the 

 experiments are more directly applicable to flume transportation, 

 since this approximates more to the conditions of the experi- 

 ments. As Gilbert notes, the principles discovered in the labora- 

 tory are necessarity involved in the work of rivers, but the 

 formulas are not directly applicable, since they depend upon com- 

 plex conditions which are essentially different in nature. Under 

 some circumstances they may be used to compare the work of 

 one stream with that of another stream of the same type. It 

 appears, however, that the results should be of great value geo- 

 logically as a basis for the further study and interpretation of 

 field observations on river action. j. b. 



2. The Mississippian Brachiopoda of the Mississippi Valley 

 Basin; by Stuaet Wellee. Illinois Geol. Surv., Mon. I, 1914, 

 2 vols., text and plates, pp. 1-508, pis. i-lxxxiii, text figs. 1-36. — 

 In this excellent monograph Professor Weller brings together all 

 that is known regarding the great wealth of Lower Carboniferous 

 or Mississippian brachiopods found in Illinois and the adjoining 

 states. The maximum thickness of the strata of this period is 

 here about 1700 feet. Of species there are 310 (85 new), dis- 

 tributed in 63 genera (4 new). The genera with more than 10 

 species are Spirifer (46), Productus (23), Ghonetes (12), Dielasma 

 (11), and Syringothyris (11). The new genus JEchinoeonchus is 

 largely if not wholly synonymous with JPustula, defined earlier in 

 the year by Ivor Thomas. Of lingulids, there are 2 genera and 8 

 species, and of neotrematids there are also 2 genera, with 13 

 species. The strophomenids are represented by 5 genera (19 

 species), productids 7(49), orthids 2(13), pentamerids 1(3), 

 rhynchonellids 10(35), centronellids 3(4), terebratulids 7(24), 

 atrypids 1(1), spiriferids 13(101), retziids 4(10), meristellids 

 3(7), athyrids 3(23). 



The author states that " it is not improbable that the sedimenta- 

 tion was continuous from the preceding Upper Devonian into the 

 Kinderhook," and yet in this work we do not find a single species 



Am. Jour. Sci. — Fourth Series, Vol. XXXIX, No. 229. — January, 1915. 

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