6 
THE MEDITERRANEAN NATURALIST 
the economic rocks of Italy; and a brief exposition 
of the geological principles that should underly 
works of this description is given. The nature 
of the various cements &c. are then entered 
into, and the lithological characters of the 
various kinds of stone are described. The 
work is profusely illustrated, with cuts re- 
presenting the antiquities of the kingdom, and 
the regions from which the principal building 
stones are obtained. 
The work has now been 30 years in course 
of preparation, and the information that it 
contains is of so valuable a nature that a copy 
of it has been ordered by the Italian Government 
for every public library, and every Chamber of 
Commerce in Italy. 
It is also to be found on the shelves of 
most of the principal institutions of Europe, 
for it is indispensable alike to the scientist and 
the capitalist. 
African Earthworms, 
The last Kew Bulletin contains a report by 
Mr. Alvan Millson, the Assistant Colonial Secre 
tary of Lagos; on Yortiba Land, the native ter- 
ritory adjacent to Lagos. After describing the 
wasteful system of cultivation employed by the 
natives and the wonderful rapidity with which the 
soil recovers from it, he says the mystery is solved 
in a simple and unexpected manner during the 
dry season. The whole surface of the ground 
beneath the grass is seen to be covered by rows 
of cylindrical worm casts. These vary in height 
from a quarter of an inch to three inches, and 
exist in astonishing numbers. It is in many place, 
impossible to press a finger upon the ground 
without tonching one. For scores of square miles 
they cover the surface of the soil, closely packed, 
upright, and burnt by the sun into rigid rolls of 
hardened clay. The rains ultimately break them 
down into a fine powder, rich in plant food and 
lending itself easily to the hoe of the farmer. 
These casts are very different in form from those 
which are common in English gardens. On digging 
down, the soil is found to be drilled in all directions 
by a countless multitude of worms drills, while from j 
13 inches to 2 feet in depth the worms are found 
in great number in the moist subsoil. It is 
impossible to estimate their number per cubic 
foot, as the quantity varies according to the 
season and the locality. Having carefully removed 
the worm casts of one season from two separate 
square feet of land at a considerable distance 
from one another, and chosen at random, Mr. 
Millson found the weight to be 10-f pounds in 
a thoroughly dry state. This gives a mean of 
over 5 pounds per square foot, and a total of not 
less than 62,233 tons of subsoil brought to the 
surface on each square mile of cultivable land in 
the Yoruba country every year. This work goes 
on unceasingly year after year, and to the untiring 
labors of its earthworms this part of West Africa 
owes the livelihood of its people. Where the 
worms do not work, the Yoruba knows that it is 
useless to make his farm. 
Estimating 1 square yard of dry earth by 
2 feet deep as weighing half a ton, there is 
an annual movement of earth per square yard 
of a depth of 2 feet amounting to not less than 
45 pounds. From this it appears that every 
particle of earth in each ton of soil, to the 
depth of 2 feet, is brought to the surface once 
in twenty — seven years. If seems more then 
probable that the comparative freedom of this 
part of West Africa from dangerous malarial 
fevers is due, in part at least, to the work 
of earth worms in ventilating and constantly 
bringing to the surface the soil in which the 
malarial germs live and breed. From speci- 
mens which Mr. Millson has sent home it 
appears the worm belongs to a new species of 
the genus siphonogaster. The type of the genus 
has been quite lately described from the Nile 
mud. Sci: Amer: 
Deep Sea exploration in the 
Mediterranean. 
The investigations which the expedition sent 
out by the Vienna Academy of Sciences has 
been carrying out in the eastern portion of the 
Mediterranean have been very successful. The 
investigations concerning the depth and general 
characteristics of the sea, and the presence of life 
in it, were carried out at seventy two distinct 
points. The greatest depths. (3700 metres, or over 
2 ^ miles), were found near the great depression 
