72 BIBLIOGRAPHY AND INDEX OF N. A. GEOLOGY, [bull. 149 
539 Penfield (S. L.) and Forbes (E. H.). Fayalite from Kockport, 
Mass., and on the optical properties of the ckrysolite-fayalite 
group and of monticellite. 
Am. Jour. Sci., 4th ser., vol. i, pp. 129-135, 1896. 
Describes the occurrence aud inineralogic and chemical characters of 
fayalite, hortonolite, and monticellite, aud the optical properties of 
chrysolite. 
540 and Pratt (J. H.). On the occurrence of thaumasite at West 
Paterson, N. J. 
Am. Jour. Sci., 4th ser., vol. i, pp. 229-233, 1896. 
Reviews previous descriptions of this mineral and discusses the chemi- 
cal and mineralogic characters of material from New Jersey. 
541 Penhale (Matthew.). Chrome ore in Quebec. 
Mineral Industry, 1895, pp. 92-93, 1896. 
542 Penhallow (D. P.). Nematophyton crassum. 
Can. Rec. Sci., vol. vii, pp. 151-156, pi. ii, 1896. 
Describes this species from Upper Silurian strata of New York. 
543 Penrose (R. A. F. 7 jr.). The ore deposits of Cripple Creek,Colo. 
Read before the Colorado Scientific Society, in Denver, Colo., June 4, 
1894, 5 pp. 
Describes the occurrence and character of the gold ores. 
544 Perrine (Charles D.). Earthquakes in California in 1895. 
IT. S. Geol. Surv., Bull., No. 147, 22 pp., 1896. 
Gives a chronologic record of earthquakes occurring in California 
in 1895. 
545 Pilsbry (Henry A.). Pleurotomaria crotaloides Morton in the 
New Jersey Cretaceous. 
Phil. Acad. Nat. Sci., Proc, 1896, pp. 10-11, pi. 1, 1896. 
546 Geology of the Mussel-bearing clays of Fish House, N. J. 
Phil. Acad. Nat. Sci., Proc, 1896, pp. 567-570, 1896. 
Describes the lithologic characters and paleontology of the beds and 
discusses the evidences of their Pleistocene age. 
547 Pirsson (Louis V.). On the monchiquites or analcite group of 
igneous rocks. 
Jour, of Geol., vol. iv, pp. 679-690, 1896. 
Describes the petrographic aud chemical characters of monchiquites 
from Montana. 
548 A needed term in petrography. 
Abstract: Geol. Soc. Am., Bull., vol. vii, pp. 492-493, 1896. 
Discusses the use of the term anhedron for those " indeterminate 
forms without crystal planes in which minerals occur, especially in 
igneous rocks." 
549 Weed ( W. H.) and. Geology of Castle Mountain mining dis- 
trict, Montana. 
See Weed (W. H.)^nd Pirsson (L. V.), No. 723. 
