Urqunart.—On the Habits of Earth-Worms in New Zealand. 271 
coarser layer, which adhered to the sub-soil. A long strip was left intact, 
and is being preserved for future observations. Similar layers, which con- 
sist chiefly of the charred wood, are to be met with in patches, at the same 
average depth, over several acres of ground. 
The section at the present time shows an even depth of 52 to 6 inches 
of black mould. The charred wood, especially where holes have been dug, 
has decayed considerably the last twelve months, reducing the average width 
to nearly $ an inch, but the layer remains horizontal and parallel to the 
surface, showing that the worms are evenly distributed, and doing an equal 
amount of work. The regular way in which the embedded objects sink, in- 
dependently of their specific gravity, as Mr. Darwin points out, “ are the 
striking features of the case." Pieces of burnt clay 14 inches in length, 
weighing over an ounce, small pebbles of jasper rock, fragments of pumice, 
and the charred wood, have all sunk to the same depth, within the same 
time, retaining an even thickness that would hardly be expected ; the 
regular depth of the mould, of course, is partially caused by the levelling 
action of rain. 
From this it appears that our earth-worms work with the same regu- 
larity as the British species, and eject—their greater number considered— 
an equal amount of earth. An addition of about 1} inches to the superfi- 
cial surface in eight years, compares favourably with the average cases 
recorded by Mr. Darwin. Of course the more rapid accumulation of mould 
the last few years, is owing to the great increase of worms—consequently 
of worm-castings ; although in uncleared lands of this description the 
annual contribution of decayed vegetable matter is in excess of grass-land, . 
its effect in increasing the thickness of the mould is not equal to the work 
of the greater number of worms. As the flat is cut off from the higher 
land by a drain, there is no sedimentary deposit; and the dust blown from 
desiccated ground is so trifling, that the present increase of mould may. be 
entirely attributed to the work of worms, 
It is probable that when a sufficient depth of vegetable—or perhaps 
more correctly animal—mould is formed for the worms to live in, that the 
annual increase of thickness decreases ; for, as a rule, under those cireum- 
stances worms do not penetrate the subsoil to any depth, except when 
driven down by dry weather. However, in the present case they burrow 
into the subsoil to a greater depth than worms generally do in the winter 
months; as it is of a loose nature it probably contains nutritious matter. 
‘It may be worth recording that in May, 1876, I placed an angular block 
of trachyte—measuring 9 inches in length, 8 in breadth, and 53 in thick- 
ness—on the same ground; in about four years it had sunk nearly 1 inch ; 
the next two years, it was in the possession of a colony of ants, who no 
