378 
ORIGIN OF LIFE IN AMERICA 
among the best indicators of past continental changes, 
and that the relations of the several southern continents as 
to their ichthyic faunas can be best understood by the assump¬ 
tion that, at some remote epoch or epochs, there was distribu¬ 
tion of land and water which eventually permitted an emigra¬ 
tion and immigration of types from one into another. Dr. 
Gunther * enunciated similar views. He thought that the 
existence of so many similar forms of fishes on both sides of 
the southern Atlantic supported the supposition that they are 
the descendants of a common stock which had its home in a 
region now submerged under some intervening part of the 
ocean. Since the days when these two great authorities pro¬ 
nounced upon this subject, the ichthyology of both Africa and 
South America has become better known, and new light has 
been thrown on the relationship between the various groups 
of fishes. We can deal with the problem now in the light of 
the latest researches. Dr. Boulenger has made a special study 
of the African fish fauna, while Mr. Regan and Professor" 
Eigenmann have paid particular attention to the ichthyology 
of South America. In his interesting address to the British 
Association on the distribution of African fishes Dr. Bou¬ 
lenger mentions Protopterus as the most noteworthy fish of 
Africa. In some respects it approaches the amphibia. It 
possesses a double lung as well as gills, and is able to live for 
a long period in dried mud. Anatomically there are many 
characters in which it differs from almost all other fishes. 
Its only living relation, Lepidosiren of Brazil, is very similar 
in form and so closely allied that the two are placed into 
the same family Lepidosirenidae. Professor Pfeffer f con¬ 
tends that since this family is represented in the Permian 
and Trias of western North America, in the Trias of India 
and South Africa, in the Cretaceous of Patagonia and the 
Trias and Jurassic of Europe it must have had a universal dis¬ 
tribution. Hence he argues that the occurrence of Pro¬ 
topterus in Africa and of Lepidosiren in South America can 
have no significance in supporting the theory of a former 
land connection between these two continents. But recent 
* Gunther, Albert, “Study of Fishes,” p. 233. 
t Pfeffer, G., “ Zoogeographische Beziehungen,” p. 433. 
