Review of Ilecent Geological Literature. 65 
too hurried examination. If new names ?it,ve absolutely necessary, let them 
be provisional until further investigations prove their right to become 
permanent. The learned author, much to his credit, is only able to rec- 
ognize between 800 and 900 species. We can agree with professor 
Dana in the statement that many apparently new species, if studied 
with sufficient care and comparison, would undoubtedly fall under some 
old species and form varieties thereof, and of this the present work will 
be a constant reminder. 
The volume is a credit to American mineralogy, and the system of 
Dana will continue to be, as in the past, the chief guide and authority for 
English-speaking students, at least in America. 
TliC Maiinington oilfield and the history of its develojnnent . By I. C. 
White. Bulletin of the Geological Society of America, vol. iii, pp. 187- 
216, with map and sections; April 15, 1892. The district here described 
lies in Marion and Monongalia counties, W. Va., on the Monongahela 
river. In each of the three sections noted at Mount Morris, Mannington, 
and Fairview, the oil wells pass through the whole thickness (1,900 to 
2,000 feet) of the Carboniferous system, from the Permian or Dunkard 
Creek series to the "Big Injun" or Mount Morris oil sand, which be- 
longs to the horizon of the Pocono sandstone, the lowest of the Carboni- 
ferous strata. The paper contains also a very interesting history of the 
development, chiefly by Profs. White and Orton, of the "anticlinal theory" 
of reservoirs of oil and natural gas, and of its successful application to 
the discovery of new locations for oil wells in the Mannington district. 
Fossil plants from the Wichita or Permian beds of T'exas. By I. C. 
White. Bulletin, G. S. A., vol. iii, pp. 217, 218; April 15, 1892. A 
collection of nineteen species of plants from the Wichita formation in 
Texas, which is regarded by Dr. V. A. White and Prof. E. D. Cope as 
certainly of Permian age on the evidence of its invertebrate and reptil- 
ian remains, is found to comprise eighteen species that occur in the 
Dunkard Creek series of West Virginia, southwestern Pennsylvania, 
and southern Ohio. The determinations of these plants were made by 
Prof. W. M. Fontaine, who, with the author of this short paper, referred 
these beds to the Permian, on the basis of their fossil flora, fourteen 
years ago. 
Notes on the Geology of the Valley of the middle Rio Grande. By E. T. 
DuMBLE. Bulletin, G. S. A., vol. iii, pp. 219-230; April 22, 1892. The 
portion of the Rio Grande valley here described, from the mouth of San 
Felipe creek, near Del Rio, to Webb Bluff, near the south line of Mav- 
erick coucty, has a length of about 80 miles. The elevation of Del Rio is 
973 feet, and the descent thence to Eagle Pass and Webb Bluff is about 
three feet per mile of direct distance, or approximately two feet per 
mile along the meandering course of the river. A slight southeastward 
dip, estimated to be about 100 feet per mile, brings successively newer 
beds into view as one travels down the valley, from the Arietina clays of 
Lower Cretaceous age at Del Rio to the Eocene beds of Webb BlulT. 
The thickness of the Upper Cretaceous strata appears to be about 7,800 
