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POPULAR SCIENCE REVIEW. 
feathery foliage, as though suddenly covered up before the foliage had time 
to decay or become water- worn. The larger branches remain perfectly round* 
and show the pith in an admirable state of preservation ; and the cellular 
tissue, filled up with mineral matter, is plainly visible to the naked eye. — 
Tide Geological Magazine , October. 
The Fossil Plants of Hungary. — Professor Unget has presented to the 
Academy of Sciences of Vienna a Memoir on the Fossil Plants of Hungary 
and Transylvania, in which he treats specially of those found by M. Stur in 
the Upper Cretaceous Deposits of Deva, Transylvania. All the specimens are 
well preserved, so that they can be recognized with certainty as belonging to 
genera allied to those of the present day ; a fact of much importance in the 
determination of the Dicotyledonous plants of the Cretaceous period. 
The “Parallel Boads” of Glenroy. — The Rev. R. Boog Watson read a paper 
before the Geological Society (Nov. 8th), in which, after a brief description 
of these peculiar “ Roads,” he gave an analysis of the two principal theories 
that have been started to account for their formation ; namely, the ice-dam 
theory and the marine theory. With regard to the first theory, Mr. Boog 
Watson stated his opinion that although it has some strong points, especially 
in respect of the coincidence between the levels of the “ Cols,” at the glen- 
keads, and those of the “ Roads,” yet, on the other hand, it is weak, inasmuch as 
the cause assigned is extremely local in its action, while the phenomena to be 
explained are very general and have a wide range, — terraces similar to those 
of Glenroy occurring in Scandinavia and elsewhere. In the author’s opinion, 
also, the ice-dam is impossible, and would be inefficient if possible ; it 
would not be water-tight, and there is no place for it in the history of the 
Post-pliocene changes in Scotland. But he remarked that objections like 
these cannot be urged against the marine theory, as the sea has been on the 
-spot, and is able to perform the work required of it. At the same time the 
author admitted that the marine theory is not free from difficulties, the 
chief being the perfection and horizontality of the “Roads,” and their 
barrenness in marine organisms ; and he concluded by .suggesting some 
explanations of these apparent anomalies. 
A combustible mud has been described to the Asiatic Society of Bengal, 
by Major Risely. It exists in large tracts, especially in the Pertabghur 
district in Oudh, where there is a swamp of it, which has the appearance of 
-ashes, but the material of which smoulders like wood. When dried, the 
mud blazes freely. It has been tried by a locomotive fireman, and found to 
produce very nearly as much steam as wood does. The Calcutta chemists call 
it an impure peat, resulting from the continual deposition of vegetable matter 
at the bottom of a marsh. It seems remarkable that the natives, though 
well aware of its properties, make no use of it ; their reason being that it 
owes its origin to “ enormous sacrifices of ghee and grain ” which former 
races burnt upon the spot where the marsh now stands. 
Origin of the Salts which compose the Earth. — Dr. Sterry Hunt has been 
contributing to the American journals a series of papers on the constitution 
-of natural waters, in one of which he gives the following theory in explana- 
tion of the origin of salts, metallic veins, and other deposits. Starting 
with the idea that at the commencement of the earth’s history, the various 
substances in ignition reacted on each other, he observes : “ The quartz, which 
