1180 General Notes. [ November, 
littoral region of the Arctic and Polar seas we find no traces of 
deep-sea corals and Brachiopoda; of vitreous sponges, Echi 
thuriz and Pourtalesiz; no trace of Crinoids, Brisingæ, Elasmo- 
poda, or of that swarm of remarkable Crustacea and fishes which 
characterize the deep-sea iauna. All these forms of animals oc- 
cur, indeed, in the Arctic seas, but here also always, only in the 
deep water, and not in the littoral region; and here the g 
contrast between the littoral and deep-sea faunas is just as sharply 
defined, and in the same manner as in warmer seas.” Many so 
called “Arctic” animals found at great depths in southern lati 
tudes, do not occur in the littoral region in the Arctic seas, but 
are there confined to the deep water as in warmer seas. Alter 
discussing the influence of temperature, the chemical conditions, — 
and the movements of the sea, Fuchs claims that light is in reality _ 
the only factor that can be taken into consideration. oe 
“Light is the most powerful factor amongst all the agents 
which influence life upon the earth, and its importance 1s gae 
ally overlooked only because, on the surface of the earth, it i8 
everywhere pretty uniformly distributed, and therefore gives but 
little occasion for the production of differences. But in the sea 
the conditions are quite different. The light as it penetrates 1mo 
the water is gradually absorbed by the water. It is thus gradi : 
ally changed, and finally entirely absorbed, so that at a certai 
depth the sea must be perfectly dark. It is to be remarked, hor 4 
ever, that the relation of the sun’s light to the water of the seas 
not perceptibly modified either by the temperature 
existing variation in the chemical composition of the 
corresponding difference of the living world. gers 
rom the experiments of Secchi, Pourtales and Bouguen, 
inferior limit of light in the sea lies between forty -three 
fathoms, this being exactly at the depth F uchs “<a 
outset as the boundary line between the littoral a doubt 
faunas. Hence, there can scarcely any longer be ‘onal 
adds, “ that the difference which is produced in the hich wed 
sea by its conditions of light is no other than that wee th 
tinguish as littoral fauna and deep-sea fauna: 1n ngpi eel 
the littoral fauna is nothing but the fauna of light, 
sea fauna the fauna of darkness. the 
Fuchs has shown, on a previous occas pourtal 
already mentioned of 43-50 fathoms, found by Sec of light; ” 
and Bouguer, cannot represent the absolute limit j 
that small quantities of light, no doubt, penetrate 
