82 BIBLIOGRAPHY AND INDEX OF N. A. GEOLOGY, [bull. 162. 
699 Sherzer ( W. H.). Limestones of southeastern Michigan, with their 
associated sandstone, salt, and gypsum. 
Abstract, Geol. Soc. Am., Bull., vol. ix, pp. 10-11, 1898. 
Describes the occurrence of Silurian and Devonian strata of the 
region. 
700 Shimek (B.). Is the loess of aqueous origin? 
Iowa Acad. Sci., Proc, vol. v, pp. 32-45, 1898. 
Describes the fauna and its bearing on the origin of the loess. Gives 
a list of loess molluscan fossils. 
701 Siebenthal (C. E.). The Bedford oolitic limestone [Indiana], 
U. S. Geol. Surv., 19th Ann. Rept., Pt. VI (continued), pp. 292-296, 
1898. 
Describes its character and occurrence in Indiana. 
702 Simpson (George B.). A handbook of the genera of the North 
American Paleozoic Bryozoa. With an introduction upon 
the structure of living species. 
N. Y., 14th Ann. Rept. State Geologist, pp. 407-608, 30 pis., 222 figs., 
1897; N. Y. State Mus., 48th Ann. Rept., vol. ii, pp. 407-608, 30 pis., 222 
figs., 1897. 
703 Sjogren (Ahe). Notes on the eastern section of Costa Rica. 
Harvard Coll., Mus. Coinp. Zool., Bull., vol. xxviii, pp. 281-282, 1898. 
Includes brief notes on the stratigraphy of the region. 
704 Slichter (Charles S.). Note on the pressure within the earth. 
Jour, of Geol., vol. vi, pp. 65-78, 3 figs., 1898. 
Discusses the magnitude of the pressure within the earth as in- 
fluenced by changes in the ellipticity of the earth's figure. 
705 Smith (E. A.). Alabama gold mining notes. 
Mines and Minerals, vol. xix, p. 129 (£ p.), 1898. 
Contains brief notes on the gold fields of Alabama. 
706 The clay resources of Alabama and the industries dependent 
upon them. 
Eng. and Mg. Jour., vol. lxvi, p. 369, 1898. 
Describes the chemical and physical characteristics and occurrence 
of Alabama clays. 
707 The stone industry of Alabama. 
Eng. and Mg. Jour., vol. lxvi, p. 398, 1898. 
Describes the occurrence and distribution of building stones in Ala- 
bama. 
708 Smith (Frank Clemens). The Potsdam gold ores of the Black Hills 
of South Dakota. 
Am. Inst. Mg. Engrs., Trans., vol. xxvii, pp. 404-428, 1898. 
Describes the occurrence, character, and origin of the so-called Pots- 
dam siliceous gold and silver ores. 
