278 Chronicles of Science. | April, 
northern. These differences indicate to a great extent the impor- 
tant conclusion to which Dr. Stoliczka has arrived respecting the 
relation existing between the orographical and geological features, 
namely, that not one of the geological zones is essentially connected 
with the geographical or orographical ranges. Whether it may 
ultimately be possible to trace any connection of this kind is a ques- 
tion of great practical and theoretical interest, and we cordially 
agree with Dr. Stoliczka’s concluding Anglo-German exclamation, 
“ Large is still the field for geologists in India!” 
The origin of prairies has recently formed the subject of three 
papers in the ‘American Journal of Science,’ by Prof. Winchell, 
Mr. Lesquereux, and Dr. Dana, in the order mentioned. Prof. 
Wiuchell believes that the prairies are of lacustrine origin and of 
post-glacial date, that all seeds contained in these lacustrine deposits 
would perish, and that the vegetation which afterwards appeared 
“ was more likely to be herbaceous than arboreal,” because the seeds 
must have been brought from distant regions. Mr. Lesquereux 
considers that the prairies were formed by a process of natural 
reclamation from the borders of lakes, mouths and banks of large 
rivers, and coasts of seas (freshwater and salt), and cites in illustra- 
tion the cases of the Mississippi, Lake Michigan, &c. He thinks 
that the nature of the soil formed under these circumstances would 
be such as to favour only the growth of sedges and grasses; and he 
endeavours to show that his explanation will account for the exist- 
ence of all known prairies and large flat tracts of land, including 
“the natural meadows of Holland,’ &c. Dr. Dana advances an 
explanation of a totally different nature, namely, that the absence 
of forests and presence of prairies are caused by the dryness of the 
climate, while conversely the presence of forests is caused by its 
moisture. Dr. Dana’s facts are indisputable and generally received, 
for everyone acknowledges the intimate relation of the moisture of 
the climate to the existence of forests; the only question is, Which 
is the cause and which the effect? Experience has shown that the 
moisture of a climate may be increased by planting forests, and 
diminished by clearing them. 
Dr. A. von Koenen has published descriptions of the Lower Oli- 
gocene fossils of Helmstiadt, near Brunswick, in the last number 
(vol. xvu., part 3) of the ‘Zeitschrift der deutschen geologischen 
Gesellschaft.’ It appears that the author has found 122 species of 
Mollusca and six corals in that locality, making in all 128 species; 
of these 17 are peculiar to Helmstadt, and one (Mautilus vmpe- 
rialis) is but doubtfully determined. Of the remaining 110 species, 
100 are known to occur in the Lower Oligocene strata of other 
localities, while only 31 have been found in true Upper Eocene 
beds, and nearly as many, namely 30 species, in Middle Eocene 
deposits. Of course Herr von Koenen, being a warm advocate of 
