273 
1876 .] Notices of Books. 
prises, besides tellurium, iron and a trace of lead. The formula 
is probably 3AgTe+(AuFe)Te. The ratio of Au to Ag is 2 : 3, 
whilst in Petzite, the mineral nearest approaching to it, the pro- 
portion is 5:8. Petzite, moreover, contains on an average 
25 per cent of gold and 40 of silver. The number of mineral 
species associated with these tellurides is strikingly smaller than 
is the case at Nagyag. 
There are further special reports on palaeontology, on zoology, 
and on geography and topography. The zoological department 
embraces Lieut. Carpenter’s report on the collections made on 
the Survey in 1873 ; destruction of pine timber in the Rocky 
Mountains ; report on the Alpine inseCt-fauna of Colorado ; list 
of butterflies collected in Colorado ; on the geographical distri- 
bution of moths in Colorado ; report on the Diptera of Colorado ; 
notice of the galls collected by Lieut. Carpenter; lists of the 
Coleoptera, Neuroptera, and Myriapoda collected by the same 
explorer ; and a variety of other valuable papers. Among the 
Coleoptera figures, of course, Doryphora decemlineata , the re- 
doubted Colorado potato-beetle, which a certain morning paper — 
proneto occasional and indiscreet dabblings in Science — describes 
as “ a kind of cockchafer.” It has never been found westward 
of the great water-shed, and appears to be travelling slowly, but 
steadily, eastwards. It does not occur at greater altitudes than 
6000 feet. 
The work is profusely illustrated with maps, plans, sedions, 
and views of remarkable geological features. 
Report of the United States Geological Survey of the Territories . 
By F. V. Hayden. Vol. VI. Washington : Government 
Printing Office. 
It appears that whilst each State of the American Union is 
executing a geological survey within its own boundaries, the 
Federal Government is performing the same task in the so-called 
Territories — the regions not yet formally organised. These sur- 
veys are being conducted in the most thorough-going and elabo- 
rate manner, and their Reports will prove documents of high 
and enduring value to the geologists, palaeontologists, zoologists, 
and botanists of the whole world. 
The volume before us — merely a small instalment of the fruits 
of this gigantic undertaking — treats of the Cretaceous Flora of 
the Western Territories. It is illustrated with thirty plates, 
containing several hundred well-executed figures of leaves, 
stones, seeds, &c., of the fossil species described, and belonging 
to the Dakota group. Of this Flora the author remarks that, 
“without affinity with any preceding vegetable types, without 
relation to the Flora of the Lower Tertiary of our country, and 
VOL. VI. (N.S.) 2 E 
