36 Revieics — Merriam's I'riassic Ichihyomuria. 



possibility of misinterpreting liis remarks is removed ; but tbis plan 

 has the almost unavoidable disadvantage of entailing some repetition 

 in statement and a want of smoothness in style, and leaves the 

 reader in doubt as to wbat the author's views may be on debatable 

 points. 



After touching in the introductory pages on tbe influence of tlie 

 mining of the precious metals upon the industrial life of the United 

 States, and especiallj^ the development of railroads, Dr. Crane 

 devotes a chapter to the history of tlie discovei-ies of gold and silver 

 in jS^orth America, the earliest date given being as far back as 1513, 

 when a cacique of gold was reported to Ponce de Leon Avhile lying 

 off the coast of Florida. The next chapter is concerned with the 

 occurrence and association of gold and silver, and includes a discussion 

 of the theory of ore formation and tbe occurrence of gold in gravel ; 

 it is followed by a short chapter on the companion question, viz. 

 their geological distribution, showing that gold is to be found in 

 rocks of all ages, contrary to the views of early geologists. The 

 inining engineer will doubtless consider the succeeding chapters on 

 the mining of the ores and gravels, the extraction of values, and 

 the production of gold and silver the most important part of the 

 book. A full and admirable account is given of the various methods 

 of mining — gravel -mining, bydraulic-mining, river -mining, drift- 

 raining, dredging : the modes of extracting the metal in wide veins, 

 in narrow veins, in bedded deposits, and in masses, typical mines 

 being described in full detail ; various important practical points 

 such as timbering, drainage, and ventilation ; and the princiiDal 

 processes, both mechanical and chemical, of obtaining the metal from 

 the ores, such as amalgamation, concentration, chlorination, and 

 cyanidation. As an appendix we find a series of valuable tables — 

 discovery of gold and silver mines and districts, occurrence and 

 mineralogical association of gold and silver, geological distribution 

 of gold and silver, yield of ores by districts and mines, yield of gravels 

 by districts and mines, fineness and value of gold and silver. A copious 

 index brings the book to a close. 



The illustrations have mostly been used before in other publications; 

 they are, especially in the case of the half-tone blocks, often far 

 from distinct and not up to the standard that might have been 

 expected. 



III. TkIASSIC IcHTHrOSATJKlA, WITH SPECIAL EEFEKENCE XO THE 



American Fokms. Ey John C. Mekriam. Mem. Univ. Cali- 

 fornia, 1908, vol. i, ^Q. 1. pp. 196, with 18 plates and 154 

 text-figures. 



SINCE 1895 Dr. John C. Merriam, of the University of California, 

 has published several small papers on Ichthyosaurian remains 

 from the Trias of California. Between 1901 and 1907 ten expeditions 

 were sent out by the University of California to collect ample material, 

 and the result was the acquisition of considerable parts of no less 

 than fifty skeletons. Dr. Merriam visited and studied the European 

 collections to prepare for the investigation of these new specimens, and 

 he has now published an exhaustive memoir on Triassic Ichthyosauria 



