446 Miscellaneous. 
justifies the following remarks of Mr. Darwin :—“ When we behold 
a wide turf-covered expanse, we should .remember that its smooth- 
ness, on which so much of its beauty depends, is mainly due to all 
the inequalities having been slowly levelled by worms. It is a 
marvellous reflection that the whole of the superficial mould over 
any such expanse has passed, and will again pass, every few years 
through the bodies of worms.” Large stones lying on the surface 
of grass-land become gradually imbedded, partly by the raising of 
the surface and partly by the undermining action of worms ; 
and the same influences have been at work, as the author well 
shows, in the covering up with a layer of mould of the remains of 
ancient buildings. 
The quantity of earth moved in this way is enormous, and such 
as to surprise those whose minds are not already familiar with the 
vast effects that are produced in nature by the long-continued 
working of minute agencies. By collecting, drying, and weighing 
the worm-casts over a given space of ground Mr. Darwin is enabled, 
at least approximately, to determine the quantity of soil brought to 
the surface by worms; and he finds that in many parts of England 
this amounts to about ten tons per acre annually. Two of his cal- 
culations, however, give a much larger amount, namely 16-1 and 
18:12 tons per acre. These larger quantities, when corrected, 
would produce a layer of about 14 inch spread over the whole sur- 
face in ten years. ‘This, of course, does not represent increase of 
thickness, but only the rate of transfer of the underlying mould to 
the surface. 
This notice has extended to such a length that we must bring it 
somewhat abruptly to a close, merely remarking in conclusion that, 
besides their influence upon the formation of mould, Mr. Darwin 
ascribes to earthworms under certain conditions an important action 
in aid of the phenomena of denudation, as their castings, when 
present on the surface, will be peculiarly liable to be washed away 
by heavy rains, and even in dry weather they will break up into 
small pellets which may easily be transported by the wind. It is 
hardly necessary to say further that for the better exposition of the 
main subject of his book Mr. Darwin thoroughly describes the struc- 
ture and habits of worms, and dwells especially upon their senses 
and mental qualities. His book is a most interesting and attractive 
one, and its teaching of the importance in nature of what are appa- 
rently the most contemptible of agents will furnish an excellent 
lesson to many besides the reading section of the general public. 
MISCELLANEOUS. 
Dutch Mollusca. By J. Gwyn Jerrreys, LL.D., F.R.S. 
WHILE passing a short time in Holland, immediately after sustaining 
the greatest calamity which can befall a man (the death of a long- 
loved wife), I spent a day at Scheveningen, a favourite sea-side 
