F TRANSACTIONS OF THE SECTIONS. 81 
Mr. Adams from the living animal at the time of its capture; and the author had 
satisfactorily identified Mr. Dillwyn’s species by means of these and other specimens 
in different stages of growth, collected by Mr. Cuming in the seas adjacent to the 
Philippine islands. The A. Owenii is distinguished from any species hitherto de- 
scribed by its laterally compressed form and prominent development of the wrinkles. 
The A. gondola is chiefly remarkable on account of the wide prolongation of the auri- 
cles on either side of the spire, whilst the keel of the shell is unusually wide, with 
~ the tubercles distant and more compressed. The lateral wrinkles are much less 
humerous than in A. tuberculosa, to which Mr. Dillwyn’s species had been ascribed, 
and do not fade into solitary warts. 
On the Influence of Temperature upon the Distribution of the Fauna in the 
Aigean Sea. By Lieut. Spratt, RN. 
After the publication, by the British Association, of the highly interesting report 
- of the distribution of the fauna of the Afgean by Professor Forbes, I was led to ima- 
gine that temperature might have a great influence on that distribution: with this 
view I pursued the inquiry by making observations on the temperature of each 
region, as opportunities offered for doing so, whilst employed on the survey of the 
Aigean seas during the summer seasons. 
These results seem to show distinctly that temperature is the principal influence 
which governs the distribution of the marine fauna. 
The summer temperature of the air in the Mediterranean is about 86°, and the 
surface temperature reaches nearly that temperature generally at that season. 
__ The zones of depth, as arranged by Professor Forbes, are as follows.—The first 
region includes all between the surface and the depth of 2 fathoms; but this he sub- 
_ divides into a superficial or tidal zone of about 2 feet, the inhabitants of which, he 
\ observes, are remarkable as being such as have a wide range in depth, eight out of the 
__ eleven species peculiar to it being widely distributed in the Atlantic. The temperature 
_ of this zone ranges from 76° to 84° during eight months in the year. Its inhabit- 
' ants are consequently subject to great vicissitudes of climate during the summer and 
' winter. Nature having thus adapted them to these conditions, we consequently 
find that they are wanderers through great geographic space, corresponding to the 
_ vicissitudes of temperature to which they are subject. 
_  Thesecond region reaches to the depth of 10 fathoms, in which, with the last sub- 
division of the first region, we have, says Professor Forbes, the characteristic fauna 
of the Mediterranean. Now the temperature in this region is seldom lower than 74° 
_ in the long summer season, and it is consequently the region upon which the Medi- 
_terranean temperature has a more permanent influence; for which reason we find 
in it the peculiar Mediterranean fauna. 
_ The third region descends to 20 fathoms, and has a decreased temperature to 68°; in 
A the fourth region it is 62° at the depth of 35 fathoms; in the sixth region the tempera- 
ture is 56° at the depth of 75 fathoms ; and in the seventh and eighth regions, to the 
_ depth of 300 fathoms, the temperature decreases only to 55 or 553°, as far as I was 
- ableto ascertain. Thus between the littoral zone and the lowest region there is a differ- 
ence during summer of 26° and sometimes of 30°; and between the second region 
4 (the Mediterranean) and the lowest, the temperature is about 20°, thus standing at 
the average temperature of a high northern latitude. After limiting the Mediterra- 
Mean fauna to the second region, Professor Forbes remarks that the third is a trans- 
5 : ition zone; but in the fourth region the Celtic character of the fauna is remarkable, 
_ there being i in that region nearly 50 per cent. of species identical of northern forms. 
___ In the sixth and lower regions he remarks, that although the identical Celtic spe- 
_ cies were fewer in the lower region, ‘‘ he found the representations of northern species 
80 great as to give a much more boreal or sub-boreal character than is present in 
i those regions where identical forms are more abundant.” 
ay Amongst the Aigean fauna are some which have a wide range in depth, there 
being nine species common to six regions, seventeen to five regions, and two com- 
mon to all, more than one-half of which are known to be wide geographic rangers. 
_ They, like the cosmopolite species of the littoral tidal zones, being thus adapted to 
climatal changes, become consequently ramblers over wide geographic space, as they 
1848, r 
Pay | 
