386 . Recent Literature. [June, 
It may even be conceived, as well remarked by J. F. Campbell, 
that such elevations might bring large areas of the earth’s surface 
` into the region of perpetual frost, thus giving rise to local glacial 
phenomena, while a warmer climate prevailed everywhere at the 
sea level. Nordenskidld declares that he sought in vain for 
evidences of ice action in the various sedimentary deposits in 
Spitzbergen. 
“Tn regard to a suggested explanation of former climatic con- 
ditions, the author may be permitted to quote the following 
language used by him in 1876: ‘ Recent speculations have 
revived the old notion of a possible change of the earth’s axis of 
rotation as a way of explaining this change of arctic climate; but 
such a phenomenon is astronomically improbable, and is also 
opposed by the fact that the direction of the oceanic currents, 
which are guided by the earth’s rotation, appears, from the distri- 
bution of marine sediments to have been the same since very 
early periods.’ Dawson has since urged the same argument, and 
reinforced it by recalling the fact that the southward migrations 
of successive floras, not less than the lines of distribution of 
the question of pre-quarternary glacial climates that we have met 
w 
The Taconic rocks are further discussed, and the name Taconian 
suggested for the lower Taconic series. These Taconian rocks 
are regarded by the author as corresponding to “ four great series 
of pre-Cambrian rocks, and mark as many successive periods in 
eozoic time.” With a reference to recent views on the origin of 
crystalline rocks, and a re-affirmation of the neptunean views of 
the author, the preface closes. 
BoranicaL Directrory.—The Botanical Directory for America 
for 1878, will be found exceedingly convenient. Part I gives the 
names of botanists and their state, while their full addresses will 
be found in Part 11, where the names are arranged by states. 
The price of this useful directory is forty cents, three copies for 
one dollar. The list is a large one, and it is only to be desir 
that a larger portion of those whose names appear were so situ- 
ated as to be able to be actively engaged as investigators. 
Watson’s InpEx to Norta American Borany.'—This 1S 4 
compact volume compiled and printed with great evident care, 
and is a laborious and useful work. It is intended to facilitate 
1 Bibliographical Index to North American Botany; or Citations of Authorities for 
Pome F; 
all the recorded indigenous and naturalized species of the Flora of North prey 
sa ‘Ss i i 
y i 
=  Polypetalłæ. Smithsonian Miscellaneous Collections. 258. Washington, March, oa 
~ 1878. 8vo, pp. 476. a8 
