40 “TERRA NOVA” EXPEDITION. 
Our knowledge of the distribution of the pelagic and deep sea fishes of the 
Antarctic Ocean is obviously not suttciently complete to permit of an attempt to 
co-ordinate the results so far obtained. 
2. THE ANTARCTIC CONTINENT DURING THE 
TERTIARY PERIOD. 
Many authorities believe that in the early Tertiary the Antarctic continent 
was connected with Australia and with South America; some think with Africa 
also. The distribution of the Fishes, and of other groups of animals, has been 
considered to support this hypothesis. 
FISHES. 
The distinctive features of the fish-fauna of the coasts of Antarctica are that 
nearly all the genera and species are peculiar and that they nearly all belong to a 
single group, the Nototheniiformes, which is characteristic of and almost restricted 
to the Antarctic and Subantarctic Zones. In the Antarctic Zone this group has 
developed into a large number of types that differ greatly in structure, appearance 
and habits. These facts seem to point to the conclusions that Antarctica may have 
long been isolated and that its coasts may have been washed by a cold sea for a 
long time, probably throughout the Tertiary Period. 
It has been suggested that identical or related species of different parts of the 
South Temperate Zone are part of the fauna of the coasts of an Antarctic continent 
that formerly connected America, Africa and Australia. It is very difficult to make 
this view harmonise with the facts. Tristan da Cunha and St. Paul, 4,500 miles 
apart, have at least two species of shore fishes (Labrichthys ornatus and Chilodactylus 
monodactylus) im common. Have these persisted unchanged whilst the coasts of 
Antarctica have receded to their present position, and whilst the fauna of Kerguelen 
has become differentiated? It seems far more likely that the distribution of these 
species is due to present conditions; Tristan da Cunha and St. Paul are nearly in 
the same latitude and on the same isotherm, and the Antarctic Drift runs directly 
from one to the other. In all probability it will be found that the species common 
to both islands have floating eggs and larvae that swim at the surface; it is even 
possible that the adult fish may occasionally migrate from one island to the other. 
The case of related species, as for example Seriolella velaini from St. Paul, and 
S. antarctica from Tristan da Cunha, may be explained on similar lines; it is 
evident that the distance between the islands is too great to be traversed by these 
species, but under somewhat different conditions the parent form may have lived 
at both and either at the Cape or at Marion and the Crozets, or at other islands 
that may have existed and served as stepping stones, but have now disappeared. 
Whatever may be the true explanation, it is certain that the construction of 
