Bd. V: 6) 
THE FISHES OF TFIE SWEDISH SOUTH POLAR EXPEDITION. 
3 
tried to apply these principles, because I think that the systematical knowledge is 
best served in this way. Unfortunately there remains nevertheless some uncertainty 
concerning which characteristics may be regarded as being of specific or only of 
subspecific value and in some cases this must be almost a matter of personal taste 
or conviction. But even with this weakness the use of a ternary nomenclature, 
when needed, appears to be better than an indiscriminate “splitting” or “lumping”. 
It is better than the “splitting”, because it permits a subordination of unequal notions 
which with this latter method is impossible when only specific names are used, so 
that two or more forms, which are nearly related and perhaps only varieties (geo- 
graphical or not) of one and the same, must appear to stand quite as much apart 
from each other as in reality sharply defined and isolated species do. The “lump- 
ing” is still more apt to bring confusion in the system, when it tends to throw 
together two or more forms which have only superficial likeness and perhaps in 
reality are only distantly or not at all related. For the study of zoogeography the 
recognition of subspecies is a great help, because it, at once, viz. already in the names, 
gives information as well about which forms belong together, as about which, through 
isolation or. other causes, have become differentiated from a common type, thus as 
well about major as minor zoogeographical districts. 
When the present author promised (p. 2 ) to describe in a separate chapter 
the fishes collected by this Expedition in the true Antarctic Region it is evident 
that he understands with the “Antarctic Region” something else than Dr. L. DOLLO, 
who in his learned treatise on the fishes of the Expedition of “Belgica” * appears 
to count to this region only the interior of the Antarctic Polar Circle although he 
admits himself that this only is a provisorical arrangement. I cannot agree with 
Dr. DOLLO in circumscribing the Antarctic Region, taken in a biological sense, in 
such a purely mathematical way. The life-zones do not and cannot coincide with 
the mathematical divisions of the earth, because the physical conditions, on which 
the former are utterly dependent, do not directly and only in a remote degree cor- 
respond with the mathematical divisions. A glance at a map, on which the isotherms 
have been laid out, suffices to show this. The experience from the Arctic Region 
proves also in the most eminent manner that the Arctic Circle has nothing to do 
with the Arctic life-zone which for instance, on the european side, is pushed back 
far above the Polar Circle, but, on the american side, extends far to the south of 
the same, a fact so well known by all biologists that it need no further explication. 
It is also known that the climatological conditions, which cause this, in their turn 
are due to the great sea currents which on the eastern side of the Atlantic move 
great masses of warm sea water towards the north and on the western side in a 
* Résultats du Voyage du S. Y. Belgica. Rapports Scientifiques. Zoologie. Poissons par L. Dollo. 
Anvers 1904. 
