Geology. 417 



8. The Mathematical Theory of Probabilities; bv Arne 

 Fisher, Vol. I, pp. XXIV, 289. New York, 1922 (The Mac- 

 millan Company). — The author who is an actuary by profession 

 has written this treatise chiefly for students of statistics, but the 

 reader will have to be an expert mathematician to follow the 

 analytical development of the theorems. In this second edition 

 twelve chapters are devoted to the theory of probabilities of 

 homogra.de statistics, by which is to be understood such series of 

 events as appear in games of chance. Two chapters are given 

 to the fitting of various analytical formulas and series to 

 statistical data or frequency distributions. The remaining four 

 chapters explain and illustrate in detail the method of computing 

 the parameters in numerical series. It is difficult to believe 

 that any set of data could justify the expenditure of so much 

 labor in analyzing the curve into what is after all but an arbi- 

 trary set of functions. The author's work is characterized by his 

 devotion to the methods of Laplace in the development of the 

 theory, and the use of the semi-invariants of Thiele, in preference 

 to Pearson's method of moments, in the calculation of the 

 parameters of the frequency function. p. E. B. 



II. Geology. 



1. The Paleontology of the Zorritos Formation of the North 

 Peruvian Oil Field; by Edmund M. Spieker. Johns Hopkins 

 University Studies in Geology, No. 3, 196 pp., 10 pis., 1922. — In 

 1867, Mr. E. P. Larkin and Professor F. H. Bradley made 

 collections of Miocene fossils in the area of Zorritos, Peru, and 

 these were described three years later by Edward T. Nelson. 

 Recently far more material was collected in this region by 

 Professor Singewald, and all of the known collections are 

 here reported on in detail. The Zorritos formation now is 

 known to have 44 species of gastropods and 57 of pelecypods. 

 Of these, 64 are new. The time appears to be in the main 

 Burdigalian, though the higher beds may be of Helvetian age. 

 The fauna is a shallow-water one, of warm waters, and cor- 

 relates best with similar faunas of Panama and the Antillean 

 areas. c. s. 



2. The Recession of the last Ice Sheet in New England; by 

 Ernst Axtevs. Amer. Geog. Soc, Research Ser., No. 11, 120 

 pp., 6 pis.. 19 text figs., 1922. — In this well printed and edited 

 book, the author describes the De Geer method of determining 

 the rate of annual deposition of ' ' varved ' ' glacial clays and also 

 the rate, of recession of the ice lobes in the lake-filled river 

 valleys. This method is, in addition, the only known one for 

 measuring earth chronology in actual years. Antevs' work 

 relates in the main to the Connecticut valley from Hartford, 



