Reviews— United States Geological Survey. 523 
Mr. Penning’s map here noticed, and its explanatory brochure, are 
welcome additions to our knowledge of the Geology of South Africa. 
Norr.—It may be added that the output of gold from the 
Witwatersrand mines was stated by the Chamber of Mines at 
Johannesburg to have been in May, 1893, 116,911 oz. 15 dwts., 
valued at £411,877 (at about £3 10s. an ounce); in June the output 
was 122,907 oz.; in July 126,169 oz.; and in August 186,069 oz., 
valued at £476,319. 
TV.—MonocraPHs AND BuiLerins oF tHE UNITED STATES 
GEOLOGICAL SURVEY. 
NOTHER batch of these most useful and valuable publications 
has just reached this country. 
Monograph xvii., “The Flora of the Dakota Group,” is a pos- 
thumous work of Leo Lesquereux, edited by F. H. Knowlton, who, 
in his preface, gives some interesting details in the life of the 
author. The work was undergoing final revision by Lesquereux 
when he died, and it has been yet further amplified by the editor, 
thus making it the most complete monograph on the subject, and 
rendering the Flora of this group one of the most thoroughly known 
to palzeobotanists. 
Monograph xviii., ‘‘ Gasteropoda and Cephalopoda of the Raritan 
Clays and Greensand Marls of New Jersey,” by R. P. Whitfield, is 
a second contribution to the paleontological knowledge of these 
beds, the Brachiopoda and Lamellibranchiata having formed the 
subject of Monograph ix. (1885). The material dealt with proved 
very unsatisfactory, consisting largely of casts, which render the 
determination, even of genera, most difficult, and though no pains 
were spared by the author his task is not yet completed, and it is to 
be hoped that in future he will meet both with better material and 
a better artist, for, with the exception of certain of the Cephalopod 
plates, the drawings are decidedly flat. 
Monograph xix., ‘Geology of the Hureka District, Nevada,” with 
an Atlas, by G. A. Hague, includes a special paper on the “ Micro- 
scopical Petrography of the Eruptive Rocks of the Hureka District,” 
by J. P. Iddings, and a “Systematic List of fossils of each formation 
in the Eureka District,” by C. D. Walcott. The Paleontology of 
the district was treated of in Monog. viii. by Mr. Walcott, and 
its Silver-Lead deposits in Monog. vii. by Mr. Curtis. The present 
work is purely geological, and is a very careful study and survey 
of a small tract of hitherto unmapped country. 
The bulletins to hand include a series of the useful correlation 
papers: No. 82 Cretaceous, 83 Hocene, 84 Neocene, 85 the Newark 
system, and 86 Archean and Algonkian (in which last are included 
“all recognizable pre-Cambrian clastics, and their equivalent 
crystallines”’). 
The sole paleontological number is 98, devoted to an account 
of “Some Insects of special interest from Florissant and other points 
in the Tertiaries of Colorado and Utah,” by 8. H. Scudder, who 
