weeks.] PALEONTOLOGY, PETROLOGY, AND MINERALOGY, 1894. To 
415& Minor (J. C, jr.), Penfield (S. L.) and. On the chemical compo- 
sition and related physical properties of topaz. 
Am. Jour. Sci., 3d ser., vol. xlvii, pp. 387-396. 
See Penfield (S. L.) and Minor (J. C., jr.), No. 449. 
416 Moeller (W. H.). The Mercnr gold deposits in the Camp Floyd 
district, Utah. 
Eng. and Mg. Jour., vol. lvii, p. 51 (correspondence). 
Describes the character and structure of the gold deposits. 
417 Mudge (E. H.). Drainage systems of the Carboniferous area of 
Michigan. 
Am. Geol., vol. xiv, pp. 301-308. 
Describes the topography and drainage systems of the Carboniferous 
area in Michigan and discusses the genesis of the river systems. 
N. 
418 Nason (Frank L.). The economic geology of Albany County [N. Y.]. 
N. Y. State Mus., 47th Ann. Rept., pp. 459-481, pis. 1-7. 
Describes the occurrence of building stones, flagstones, clays, and 
sand banks in this county. 
419 Economic geology of Ulster County [N. Y.]. 
N. Y. State Mus., 47th Ann. Rept., pp. 569-600, pis. 1-5. 
Describes the occurrence of Rosendale or natural cement and the 
building stone and clays of this county. 
420 Origin of the iron pyrites deposits in Louisa County, Va. 
Eng. and Mg. Jour., vol. lvii, pp. 414-416. 
Describes the vein formation of these ore bodies, compares them 
with the New Jersey iron ore deposits, and discusses the evidence as to 
the origin of the ores, and suggests that they were leached out from 
the shore rocks at the time of deposition of the inclosing sedimenta- 
ries, and were precipitated contemporaneously with the formation of 
the latter. 
421 [The lead and zinc deposits of the Mississippi Valley.] 
Am. Inst. Mg. Engrs., Trans., vol. xxii, pp. 636-642. 
In discussion of paper by W. P. Jenney on the same subject. 
422 The chemical composition of some of the white limestones of 
Sussex County, N. J. 
Am. Geol., vol. xiii, pp. 154-164. 
Gives several chemical analyses of the limestones in this county, 
and discusses the evidence indicating that the white crystalline lime- 
stone and the blue " magnesian " limestone are of contemporaneous 
origin. 
423 Summary of facts proving the Cambrian age of the white 
limestones of Sussex County, N. J. 
Am. Geol., vol. xiv, pp. 161-169. 
Gives a summary and discussion of the evidences which indicate that 
the white limestones, heretofore considered to form a part of the Azoic 
crystalline rocks, belong to the Cambrian formation. 
