ORTMANN : TERTIARY INVERTEBRATES. 315 
Finally Osborn (1900, p. 565 and map on p. 566) accepts fully the 
theory of Antarctica, and, in the main, follows Forbes, although his recon- 
struction of this old continent by elevation to the 3040-meter sounding 
line is not quite as extensive as that of Forbes. In this respect Osborn’s 
view is intermediate between Forbes’ and Fledley’s, and decidedly 
approaches our conception. 
Thus we see that of the various theories advanced for the explanation 
of the similarity of the southern faunas, the theories of Gill, Wallace, and 
also the second theory of Hutton have not been considered seriously by 
subsequent writers, while the oldest one, formulated by Ruetimeyer, has 
furnished the fundamental idea for them. One of them, Forbes, has 
pushed this idea to an extreme, which we cannot accept by any means, 
while Hedley has attempted to restrict it to reasonable proportions, and 
to reconcile it with the zoogeographical facts as well as with the present 
conditions of distribution of land and water in the southern hemisphere. 
In this sense, Hedley’s specification of the Ruetimeyer-Hutton theory is 
the most conservative, especially as compared with Forbes’ fancies, and 
it is only natural that we should accept his ideas as the most probable of 
all, that is to say, we accept the first theory of Ruetimeyer and Hutton , 
with the restrictions put upon it by Hedley . 
For our present purpose, this acceptance of the theory of the former 
existence of an “Antarctica” means that we are of the opinion that the 
elements of the fossil Patagonian fauna resembling certain forms in 
New Zealand and Australia are to be regarded as an additional proof 
of the former connection of South America with Australia and New Zea- 
land. Since the respective shells are all preeminently inhabitants of the 
littoral, of shallow water, and since it is very probable that they were 
unable to cross over large extents of deep sea, a region of shallow water 
must have formed a connection between both parts, and nothing is more 
natural than to assume that this shallow water accompanied the coast line 
of ancient “Antarctica.” It does not necessarily follow that this coast 
line was a continuous line along the uninterrupted shores of a truly con- 
tinental mass, but it may have consisted of a chain of islands, at least in 
part. As Hedley urges, we should not regard the Antarctica as a solid 
continent, but probably it was broken up at certain times into parts, which 
were united again in one or another direction. This assumption seems 
to be chiefly supported by the evidence furnished by land animals, and 
will be discussed elsewhere in this work. 
