260 
THE MEDITERRANEAN NATURALIST 
for a smooth perpendicular wall or rock. They 
devour vegetation generally, utterly devastating 
the country over which they pass. These creatures 
are lemmings, which have increased to enormous 
numbers, until, seemingly made desperate by 
hunger, they leave their usual haunts, and, prey 
upon by bird, beast and fish, with constantly thin- 
ning ranks, make their irresistible march across 
the land, to end usually in almost total annihila- 
tion in the sea. The lemming is scarcely six 
inches long, yet even in its forest home it fiercely 
disputes the passage of man or of dog. It belongs 
to the same subfamily of rodents as the vole, or 
short-tailed field-mouse, which has caused great 
destruction in Scotland during the present year, 
and which is said to exist in greater numbers than 
any other mammal in Europe, Asia and America. 
“Left Handed” Snails 
Physiologist have found it a difficult matter to 
account for the facts that most people are right- 
handed and a few left-handed. In a recent work, 
Sir Daniel Wilson concludes that left-handedness 
is due to an exceptional development of the right 
hemisphere of the brain, and traces the phenomenon 
back to the early stone age, certain implements 
indicating that paleolithic man was sometimes 
left-handed, and certainly was not ambidextrous, 
as some have maintained. Among the lower animals 
are individuals that use the left limbs more readily 
than the right. Dr. D. G. Brinton adds that, 
while it may sound like a “bull” to talk of animals 
as left-handed who have no hands, the same 
physiological phenomenon is observed in snails. 
In them it is manifested as a reversed twist of 
the shell. With the ordinary vine snail the spiral 
curves from left to right, but in one specimen in 
about 3000 the curve is from right to left; and in 
certain other mollusks examples are far more 
common. 
The Depths of the Mediterranean and 
Black Seas. 
By Rjchard Bkynon, F.B.G.S. 
( Concluded.) 
From 80.8° F. to 69 F. was the thermometric 
range in the first 27 fathoms. In the next 27 
fathoms the temperature fell to G2.5° F. The 
for depths between 110 and 547 fathoms was 59 F. 
to 57'F. At the lowest depth found (2406 fathoms) 
the temperature was 56'°F., which, as previous 
investigators have established, is the approximate 
j uniform temperature of the bed of the Mediter- 
* ranean. One very curious result of the temperature 
experiments was the finding of water whose 
temperature was 52AF., at a depth of 415 fathoms, 
at the junction of the Adriatic with the main 
waters of the Mediterranean Sea. 
It has been found that the temperature of the 
Mediterranean Sea bed is by no means constant, 
and, according to some authorities, varies slightly 
in accordance with the mean temperature of the 
winter preceding the season in which the tempera- 
tures of the sea bottom are taken. Thus in ! C 71 
the Shearwater expedition, under Captain Nares 
and Dr. Carpenter, found a bottom temperature at 
1650 fathoms of 56", and the year previous the 
same temperature had been met with at a spot 
where the sea bed was 1743 fathoms from the sur- 
face. In 1881, however, Captain Mangnaghi, 
Hydrographer to the Italian Navy, along the Pro- 
fessor Giglioli, in the surveying vessels libs/. ingti n 
found the bottom temperature to be 1° higher than 
that recorded as the mean of those obtained in 
1871. The mean temperature of the months of 
December, January, February, March, and April 
is 53.6°F. at Toulon and 56.84° F. at Algiers, and 
the average of these two temperature gives appro- 
ximately the degree of heat contained in the Me- 
diterranean Sea bed between those two places. 
With regard to the Adriactic Sea. soundings show 
that only one-third of its area can be regarded as 
forming a part of the Mediterranean basin proper, 
the remaining portion not averaging more than 50 
faths. in depth. A channel of 400 fathoms in depth 
stretches across the entrance to the sea, from 
Otranto to Albania. Within the sea the depth 
increases until a maximum of 765 fathoms is at- 
tained, and this rapidly shoals until the compara- 
tively shallow waters of the northern portion of 
the sea are encountered. The Pola made some 
interesting experiments relative to the transpa- 
rency of the Mediterranean waters. In three cases 
a white disc was seen down to a depth of 177 feet 
Where the water was deepest, however, invisibility 
was reached at 105 feet. 
