Geology and Mineralogy. ei iy) 
seams over eighteen inches in thickness, above 108,000,000,000 tons, 
which is “three times that of the estimated available bituminous 
and semi-bituminous coals of Pennsylvania.” 
10. Geological Report of New Jersey for 1885. 228 pp. 8vo. 
—Speaking of the junction of the Potsdam sandstone and Archean 
in New Jersey, at two localities in Sussex county, Professor 
Coox states that the actual plane of contact is obscured by the 
occurrence of so much feldspar in the sandstone as to present the 
appearance of a gradual transition into the older rock. Besides 
the general feldspathic character of the Potsdam, fragments and 
masses of the Archzean are imbedded in it. ‘These facts are simi- 
lar to those that have been reported from the vicinity of the 
junction both north and south of the Archean, on the west side 
of the Hudson River. They tend to show that the Triassic was a 
valley or estuary formation. ; 
A map of Sandy Hook in the report, facing the title page, 
gives, beside the outline for 1885, the outlines from a survey in 
1685, also in 1765, and later lines from the U.S. Coast Survey. 
The increase in length and breadth since 1685 has given more 
than four times the area it then had. A map is given of Little 
Egg Harbor showing, since 1841, that the drifted sands have pro- 
longed the north point of the entrance nearly 3 m. 8.W. and 
closed the old inlet. At Holly Beach a similar change has 
taken place by a southward drift of the sands along the beach, 
‘which has also shortened in the north end. 
11. Freshwater Invertebrates of the N. A. Jurassic.—Bulletin 
27 of the U. 8. Geological Survey is occupied with a paper by 
Dr. C. A. Wut on the freshwater invertebrates from the Juras- 
sic rocks of Dakota, Colorado and Wyoming. The genera of 
shells represented are Unio (7 species), Limnaa (3), Planorbis, 
Vorticifex, Valvata, Viviparus, Lioplacodes, Neritina ; and the 
Ostracoda, according to the best English authority, Professor T. 
Rupert Jones, to whom they were submitted, include Metacypris 
Forbesii Jones, besides other species of the same genus, Darwin- 
ula leguminella Forbes, and several yet undescribed species of 
Cypris. The memoir is illustrated by four plates. 
12. Modern Petrography, an account of the application of the 
Microscope to the study of Geology ; by Grores H. Wirtiams. 
35 pp. Boston, 1886 (Monographs on Education, D. C. Heath & 
Co.)—This is an interesting essay, telling of the methods of 
microscopical Petrography,.and calculated to give to the reader 
something of the enthusiasm for the subject which is felt by the 
writer. Its usefulness to teachers is increased by the bibliogra- 
phy, suggestions as to instruments, etc., given at the end. 
13. Stromeyerite from Mexico.—Dr. Konig has analyzed a 
Specimen of stromeyerite from Zacatecas with the- following 
results : 
Ss Ag Cu Insol. 
15°81 50°18 33°69 0°26 = 99°94 
This corresponds to the formula (Ag, Cu),S with the ratio of 
silver to copper sulphide nearly 1:1, or exactly 47:53. The min- 
