THE FISHES OF ALASKA 
89 
likewise lives in the Mississippi and its tributaries, while its 
next of kin, Psephurus gladius, occurs in the Yangtse Kiang 
and Hoang Ho rivers in China. These also are ganoid fishes 
and, like the true sturgeon and bony pike, are the only few 
remaining members of a very ancient and formerly abundant 
group of fresh-water fishes. The fact of their survival in 
these two continental centres might tempt us to adduce these 
instances in support of the theory stated above, that Asia 
and North America were recently connected with one another 
by land, whereas the migration of these fishes is an old story 
dating back to some remote geological period when their ances¬ 
tors no doubt spread from one continent to the other by means 
of a land connection which probably lay further south. Their 
geographical distribution has obviously nothing to do with 
the subject under discussion, which concerns a geologically 
recent event. The cat-fishes or horned-pouts (Ameiurus) 
are possibly of a more recent origin. They swarm in every 
quiet stream and pond, especially in the eastern States pf 
America. A single species (Ameiurus cantonensis) is found 
outside the American continent, viz., in China. Finally 
I may mention that the “ suckers ” (Catostomus), which are 
very numerous in the American streams, are confined to 
North America, with the exception of one species (Catos¬ 
tomus rostratus), which inhabits eastern Siberia. The last 
case certainly indicates a former land connection between 
North America and Asia, and consequently a dispersal from 
the former to the latter, at a geologically recent date. Still 
in the present state of our knowledge we are unable to deter¬ 
mine whether the passing across to Asia of these fishes coin 
cided with that of the great mammals whose dispersals I 
have endeavoured to elucidate. 
It is impossible to discuss the relationship of all the Asiatic 
to the Alaskan groups of animals, but no matter what class or 
order we examine with a view to testing this kinship, we 
find among almost all of them some indications of it. Hr. 
Horvath,* for instance, recently dwelt on the large number of 
species of Hemiptera (a group including bugs and allied 
insects) common to Europe and North America. He quoted no 
* Horvath, Gr., “ Faunes hewipterologiques,” p. 7. 
