320 
THE MEDITERRANEANS' NATURALIST 
The greater part of the latter consisted of the j 
remains of several species of deer, similar remains 
of which were also found to occur in the Pleisto- 
cene beds at Duera (1) and Tal Asiri in Gozo; 
and of a species of Helix which is no longer found 
to esist in the islands. 
The state of mineralization in which the 
bones were found was most complete; and 
when in addition to these facts we take into 
consideration the height at which the cavern is 
now situated above the present valley bed, and the 
period that would be required to excavate the 
valley to its present depth; the character of the 
climatal conditions which effected such wholesale 
degradation as the district around bears testimony 
to, and of the time which must have elapsed 
between then and the establishment of the present 
favourable conditions; and lastly of the fact that 
the Phoenician, Punic, and Greek remains and 
their surroundings, that are found in the denuded 
portions of the islands offer no evidences to show 
that the rate of degradation of the islands’ surfaces 
has increased or diminished during the last two 
thousand years, or that the climatal conditions 
were much different then to what they are now — 
when these and the other equally important points 
referred to in my report are duly weighed I think 
we should be justified in assigning to the remains 
of the prehistoric man found in the HarDalamCave 
an antiquity that would carry us back to an epoch 
considerably more remote than that to which 
Diodorus and Pliny refer in their accounts of the 
people who, hundreds of years before the Christian 
era exerted their civilizing influences from the 
banks of the Tigris to the British Cassiterides. 
The Malta Potato Disease. 
In a paper contributed to the “Journal of the 
Royal Agricultural Society of England.” Mr. Chas 
Whitehead gives some interesting and valuable 
details of the results of certain expriments which 
were recently tried for the prevention and cure of 
the potato disease. 
According to his report there is a unanimous 
verdict on four points. 
1. That the dressing with the sulphate of cc, ner 
and lime solution which was recently given in 
the Mediterranean Katuralist, though it doe? 
not entirely prevent disease, has a marked 
effect in lessening the extent to which the 
disease appears. 
2. That associated with the lessening of the disease 
is an almost certain increase of crop, which 
more than pays for the cost of application of 
the dressing. 
3. That the best treatment is an early application 
of the mixture before disease has made its 
appearance, and that this should be repeated 
if the marks of the first dressing have been 
removed by rain. 
4. That even if delayed until disease comes a 
lessening of the spread of disease may to some 
extent be effected by a late dressing, and the 
crop will, as a rule be sufficiently increased to 
pay for the application. 
After this very clear pronouncement the use of 
this mixture ought to become general among 
Maltese potato growers. 
The Relationship of the Structure of 
Rocks to the conditions of their 
Formation. 
By H. J. Johnstox La vis, y.d.,f.c,.s.. etc. 
Quartz appears never to have been produced 
artificially, except from solution in water of sili- 
cates of a glass at a high temperature and pres- 
sure by Daubrbe; and from the abundance of 
fluid cavities seems to be the result of (in rocks) 
hydrothermic origin under very great pressure. 
Leucite , although a mineral of local occurrence, 
is of deep interest to the petrologist. It has never 
been met with amongst furnace slags, except as a 
sublimation. M. Hautefeuille (1) obtained mea- 
surable crystals by fusion of the components of 
leucite in vanadate of potash. Fouque and M. 
(1) Annales Scient. de l’ E cole norm. sup. '2nd 
series, vol. ix., 1SS0. 
(1) Coolce J.H , “ On. the Pleistocene Beds at 
Gozo ” Geol. J Lag. Vol. VIII., p. 326., Aug. 1S01. 
