50 BIBLIOGRAPHY AND INDEX OF N. A. GEOLOGY, [bull. 146. 
256 Keyes (Charles Kollin). Economic geology of Des Moines County 
[Iowa]. 
Iowa Geol. Surv., vol. iii, 2d Ann. Rept., pp. 411-492, pis. xxxiii- 
xxxvii, with geologic map. 
Describes the topographic character of the region and the distribu- 
tion, lithologic character, and structure of the Carboniferous and Pleisto- 
cene formations. Gives sections exposed at different places and men- 
tions fossils found. Describes the occurrence of building stone, clay, 
coal, and lime. 
257 Paleontology of Missouri, Part I. 
Mo. Geol. Surv., vol. iv, 1894, pp. 271, pis. i-xxxii, figs. 1-9, with geologic 
map of the State. 
Describes the lithologic character, distribution, and structure of the 
Archean, Algonkian, Silurian, Devonian, and Carboniferous formations in 
Missouri, and includes descriptions of protozoans, sponges, corals, echi- 
noderms, and crustaceans, and a stratigraphic catalogue of Missouri 
fossils. 
258 Paleontology of Missouri, Part II. 
Mo. Geol. Surv., vol. v, 1894, pp. 266, pis. xxxiii-liv, figs. 10-11. 
Describes the specific characters of polyzoans, brachiopods, lamelli- 
branchs, gasteropods, cephalopods, and vertebrates occurring in Mis- 
souri, and includes a synonymic index to the fossils of Missouri. 
259 Secular decay of granitic rocks. 
Iowa Acad. Sci., Proc, vol. ii, pp. 27-31, pis. ii-iv. 
Describes the disintegration of granitic rocks of Maryland and Mis- 
souri, and discusses the general process of secular decay of similar 
rocks. 
260 Synopsis of American Paleozoic echinoids. 
Iowa Acad. Sci., Proc, vol. ii, pp. 178-194, pis. xviii-xx. 
Remarks on the general characters and distribution of echinoids, and 
describes and figures a number of species. 
26 L Opinions concerning the age of the Sioux quartzite. 
Iowa Acad. Sci., Proc, vol. ii, pp. 218-222. 
Reviews previous opinions as to the age of this formation, and men- 
tions finding impressions resembling certain lamellibranchs. 
202 The Cambro-Silurian question in Missouri and Arkansas. 
Jour, of Geol., vol. iii, pp. 519-526. 
Reviews previous papers concerning the age of the sedimentary rocks 
of the Ozark series in Missouri and Arkansas, and discusses the evi- 
dences of the stratigraphic succession and age of the beds which make 
up this series. 
26.3 Acidic eruptions of northeastern Maryland. 
Am. Geol., vol. xv, pp. 39-46. 
Describes the granitic rocks of northeastern Maryland, discusses the 
evidences of continual changing in the physical condition of rocks, and 
remarks on the economic value of the Port Deposit granite. 
264 A hypsometric map of Missouri. 
Am. Geol., vol. xv, pp. 314-317. 
Mentions the different sources from which data have been obtained 
concerning the elevation of different localities in the State, and presents 
a sketch map showing the location of lines of precise leveling and of 
railway lines whose levels are used for primary control. 
