CORRESPONDENCE. 243 
be looked upon as a mere list of long names. It is, however, a 
contribution of great value, both for historical information as to 
the founders of the genera, and also as a reference catalogue 
and a bibliography combined. Bulky as the paper is, it cannot 
convey to any but a practical botanist an idea of the immense 
labour of research which must have been devoted to its prepara- 
tion. It forms an important and necessary appendix to the 
otherwise incomplete “ Flora Australiensis.” 
CORRESPONDENCE. 
—_——_<> —_. 
EARTH-WORMS IN NEW ZEALAND. 
(To the Editor N.Z, JOURNAL OF SCIENCE, ) 
S1rR,—Our late illustrious master, in his valuable work on 
“Vegetable Mould,” states (p. 146)—“ Worms appear to act in 
the same manner in New Zealand as in Europe ; for Prof. J. von 
Haast has described a section near the coast” (“Trans. N.Z. 
Inst.,” vol. XII, p. 152). As no further mention is made of our 
earth-worms, a few observations may not be without some 
interest. 
In October, 1875, I dug a trench in some newly-cleared 
land—a raised beach, Manukau Harbour. The section showed 
about 4% inches of black mould, and a horizontal layer, 1 inch 
thick, of burnt clay, wood ashes, small stones, and pumice, lying 
on brownish-green arenaceous clay. The vegetation cleared was 
the growth of about 30 years. A portion of the land was left 
undisturbed. Measurements taken a few days ago give an 
average of 1% inches turf, 534 inches black mould ; there was 
no perceptible difference in the layer of ashes. An angular 
block of Trachyte—about 25lbs.,—placed in May, 1875, has 
sunk 1 inch, allowing for the turf. After reading Darwin’s 
work on “V.M.,” I made some systematic estimates of the 
number of worms per acre; and I have taken advantage of the 
recent heavy rains of again making an approximate estimate. 
The results are considerably higher than Henson’s, and I should 
have hesitated to publish them had I not been in a position to 
prove my assertions. Henson (“V.M.,” p. 158) calculates there 
are 53,767 worms per acre in garden mould; about half that 
number in corn-fields. My estimates, founded on digging about 
Yy acre, and a large number of tests in various parts of the 
_ fields—some in pasture for upwards of 16 years—gave from 4 to 
26 worms per square foot. The alluvial flats, slopes, and richer 
portions of the upper lands would certainly average 8 per square 
foot, or 348,480 per acre ; about half that number in the inferior 
erass lands. In uncultivated fern lands worms are scarce, but 
they affect the edges of swamps in considerable numbers, and 
contribute largely in forming the good soil generally found 
there, working backwards year by year up the ridges when the 
