Reviews — United States Btdletins. 91 



by a subsidence of the continent, and a new invasion of the Mississippi 

 seas introducing Lower Carboniferous time." 



The Paleography of the Devonian is illustrated by a series of maps. 

 The bulk of the volume comprises the details of the stratigraphy 

 of the Lower Devonian rocks, and of the range and distribution of 

 the fossils : this part is by Drs. Schuchert, Swartz, T. Poole 

 Maynard, and K. B. Rowe. The systematic paleontology is by 

 Drs. Schuchert, Swartz, Maynard, D. "W. Ohern, E. 0. TJlrich, and 

 E-. S. Bassler. 



Vol. VI, Middle and Upper Devonian (pp. 720, with 2 text-figures, 

 6 plates, also 38 of Middle Devonian and 29 of Upper Devonian fossils 

 in atlas). In this volume we have full particulars of the strata, 

 of the correlation of subdivisions, the distribution and range of 

 species, and the relations of the faunas to the sediments. The 

 general stratigraphic and paleontologic work is by Professor Prosser, 

 Dr. E. M. Kindle, and Dr. Swartz ; the systematic paleontology of 

 the Middle Devonian is mainly by Professor Prosser and Dr. Kindle, 

 with contributions on Bryozoa and Ostracoda by Dr. E. 0. TJlrich 

 and Dr. It. S. Bassler; and the systematic paleontology of the 

 Upper Devonian is by Dr. J. M. Clarke and Dr. Swartz. 



The illustrations in the two volumes of text comprise effective 

 views of formations' and scenery, and a series of columnar sections. 

 Yol, VII consists of the Atlas of Plates, 149 in number. Many new 

 species are figured, while among European forms we note Hindia 

 sphceroidalis, Dune, Favosites basalticus, Goldf., Halysites catenulatus, 

 Linn., from the Lower Devonian ; Atrypa reticularis, Linn., from 

 Lower, Middle, and Upper Devonian ; and Schizophoria (OrtJiis) 

 striatula, Schloth., Spirifer disjunctns, Sow., and Btichiola [Cardiola) 

 retrostriata, v. Buch, from the Upper Devonian. TT B "W 



VIII. — Bulletins issued by the United States Geological Sohvey. 



Bulletin 521. The Commercial Marbles of Western Vermont. 

 By T. Nelson Dall. pp. 170, with 17 plates (including 2 maps) and 

 25 figures in the text. 1912. — There is already an extensive literature 

 on the geology of the * marble belt ' of Vt^estern Vermont, and the 

 present bulletin is designed to summarize the previous work, 

 providing those interested in the marble industry with a clear idea 

 of the geological structure of the district and of the microscopic 

 structures of the various marbles. In describing the relations of 

 the calcite to the dolomite in the area, the author points out that 

 repeated alternations of calcite and dolomite bands are frequent : 

 tliis can only be explained by assuming repeated changes in the 

 conditions of sedimentation to have taken place. The mineral con- 

 stituents and microstructure of the marbles are described, and are 

 illustrated by numerous text-figures, and a clear account is given 

 of the geological structure of the area. There is a useful glossary 

 of technical terms and a good index. 



Bulletin 522. Portland Cement Materials and Industry in 

 the United States. By Edwin C. Eckel, with contributions by 

 r. Burchard and others, pp. 401, with 19 maps and 2 diagrams. 1913. 



