SCIENTIFIC SUMMARY. 
205 
Occurrence of the 11 Primordial Fauna ” in Nevada. — Mr. J. D. Whitney 
has had placed in his hands specimens of fossils from the above locality by 
Professor Joseph Le Conte, who obtained them from Mr. J. E. Clayton. 
(See Silliman’s “American Journal/’ February 1872.) These fossils indicate 
most unequivocally the Potsdam period of the Silurian age, since they be- 
long to those most characteristic families, the Lingididce and the Para- 
doxidce. The specimens contain a great number of individuals, but few 
species ; and these much broken and closely compacted together. Among 
the fragments are several heads of Agraidos ( Arionellus and Arion of Bar- 
rande, Crepicephalus of D. D. Owen), and the species seems to be the same 
A. Oweni which has been described by Meek and Hayden as occurring in 
the Big Horn Mountains. This is by far the most abundant species in the 
specimens obtained by Mr. Clayton; but there are also other fragments, 
one of which seems almost certainly to be a Conocoryphe (Conocephalites of 
Barrande), and others to belong to the genus Paradoxides. The class of 
brachiopods is represented in these specimens by two or more genera, all of 
the family of Lingididce. Among these he thinks that he is able to recognise 
the genera Lingulepis (Lingula) and Oholella. At all events, the character of 
this assemblage of fossils is thoroughly and peculiarly Primordial. This is 
an interesting discovery, since it carries the Primordial fauna much farther 
west than it had been found before. The most western locality of Potsdam 
sandstone fossils previously described, is that in the Big Horn Mountains, at 
the head of Powder Biver, in longitude 107°, while that discovered by Mr. 
Clayton is near the 116th meridian. It is indeed wonderful to see the 
persistence of this grouping of forms which characterises the lowest sub- 
division of the fossiliferous series, and which has been found recurring at so 
many points over the vast area of the American continent, as well as on the 
other side of the Atlantic. 
Geological Survey of England. — The new edition of Sheet 7 of the Geo- 
logical Survey Map of England, showing all the drift deposits on the scale 
of one inch to one mile, has just been published. It is a considerable 
improvement on the old map. A glance at the old edition, says the “ Geo- 
logical Magazine ” for March 1872, comparing it with this new one, shows 
at once the great utility of mapping all the superficial deposits, for not only 
have they a high economic value, but in their relations to drainage and 
health — an inquiry which we are glad to observe is attracting public atten- 
tion — their importance cannot be over-estimated. The area comprised in this 
sheet, about 800 square miles, includes the western part of London. It is 
bounded on the east by Hornsey and Enfield ; on the north it takes in 
Hatfield Park, St. Albans, Hemel Hempstead, Great Berkhampstead and 
Wendover ; on the west it extends beyond Princes Risborough, Great 
Marlow, and Twyford in Berkshire ; while to the south it includes Windsor 
and the Great Park, Staines, Twickenham, Wimbledon Park, and Dul- 
wich. 
Mineral Veins have their Origin in Solfataras. — This is the view taken by 
Mr. J. Arthur Phillips in a paper published in the “ Philosophical Maga- 
zine” [Dec. 1871]. The most interesting of the Solfataras, or fissures 
giving off steam, are those known as the Steamboat Springs in the State of 
Nevada, where some of the crevices are over 1000 yards in length, and are 
