160 
THE MEDITERRANEAN NATURALIST 
for December. Leaving the Adriatic at Gape 
Leuca, the Pola proceeded south to the latitude 
of Navarino; thence she ran south-east to Canclia, 
visiting also Cerigo Island and Santorin. Sailing 
round the eastern part of Candia, the Pola pro- 
ceeded to Alexandria, west along the African coast 
to Bas Milhe, thence to Candia again, along the 
south-western coast of that island, to Cerigo, Milo 
and the Pyrseus. The soundings during this cruise 
were extremely interesting, inasmuch as in lati- 
tude *35° 44' 20" and longitude 21 r 44" 50" (about 
50 nautical miles south-west from Cape Matapan) 
the Pola found the depth of 4400 metres (2406 fa- 
thoms), followed within a few miles further east 
by a depth of 4080 metres 72236 fathoms), which 
are the greatest depths recorded in the Mediterra- 
nean. They have received from the Austrian Hy- 
drographical Board the name of Pola Deep. The 
great depression of the Mediterranean must thus 
be shifted considerably east from its former cen- 
tral position on our maps. Another deep area was 
explored between Candia and Alexandria — the 
depths attaining from 3310 metres (1810 fathoms) 
some 20 miles south-east of Grandes Bay, and 
from 2392 metres (1208 fathoms) to 2120 metres 
(1322 fathoms) -within a short distance from Alex- 
andria; the maximum depth sounded being 3068 
metres (1678 fathoms) in 28° 39' 30" north latitude 
and 33° 19' 54" east longitude. The full results of 
the numerous and varied observations made on 
board the Pola will be published when all calcu- 
lations have been completed; but several interest- 
ing facts are already indicated in the preliminary 
report. The highest temperatures were found in 
the first parts of the voyage, and are given as fol- 
lows:— -Prom 80‘8° F. to 69° in the first 50 metres 
(27 fathoms); from 69° to 62'5° in depths from 50 
to 100 metres (27 to 55 fathoms); from 59° to 57° 
in depths of from 200 metres (110 to 547 fathoms) 
to 3000 metres (1640 fathoms). The lowest tem- 
perature (52|°) was observed at the issue from the 
Adriatic Sea, at a depth of 760 metres (415 fa- 
thoms); at 4400 metres (2406 fathoms) the tempe- 
rature was 56°. It was observed last year that in 
the Central Mediterranean the density of the 
water and its saturation with salt increased with 
depth, and the same was observed in the western 
part of this year’s cruise. But in the Eastern Me- 
diterranean the density of water varies but very 
little in the different strata (from P0297 to P0300), 
and it is higher on the whole than in the West. 
The transparence of the water is very great in the 
Eastern Mediterranean; in three cases a white 
disc was seen down to a depth of 54 metres (177 
feet), but it disappeared from view at a depth of 
32 metres (105 feet) at the above mentioned station 
in the south-west of Cape Matapan. Many data 
relative to the colour and transparence of water in 
connection with the weather were collected, and 
they will be analysed in subsequent reports. On 
the whole, no less than 50 deep-sea soundings 
were made — 27 soundings reaching depths of more 
than 100 metres (547 fathoms). Prof. Luksch’s 
paper is accompanied by a map. 
Proc. Roy. Geog. Soc. 
Diseases of the Malta Orange. 
In the reply to a letter sent by the late Major- 
General Hales Wilkie respecting the causes of the 
diseases of the Malta Orange, Prof: Tar: Toggetti 
of the Boyal University, Florence writes. “I have 
the honour to acknowledge the receipt of your 
communication respecting the Maltese Orange 
pest, and having received several days later speci- 
mens of the insect of which you speak, I now 
hasten to comply with the request contained in 
your letter. First of all I find that the flies sent 
to me, both male and female, correspond exactly 
in their more prominent characters, as in their 
antennae and frontal parts, with other flies, which 
in the year 1881 were seen in Sicily and which 
cause considerable damage not to the orange 
cultivated -there, but to the fruit of the nectarine. 
I referred the specimens to the genus Ceratites. 
McLeay, ( Petalophora Macq. Tephritis, Wiedm.) 
and I considered it to be C. hispanicus , a species 
which was determined by Bremen from specimens 
brought from Spain into Italy some time before 
by the illustrious Gliiliani. 
This species is, however, so similar to the form 
described by McLeay under the name Cera.titis 
Citriperda that Ghiliani without contesting the 
name is inclined to consider it as being a variety 
of the same. 
This fly has been se-’eral times identified by 
Ghiliani as C.capitata {Tephritis capitata Wiedm), 
and I am also of the same opinion after the 
description of the figures that I have now seen. 
