hat there is a species in the Upper Nile and in
West Africa.

The acanthopterygian family (_Labyrinthici_) contains nine freshwater
genera, and these are distributed between the East Indies and South and
Central Africa.

The Carp fishes (Cyprinoids) are found in India, Africa, and Madagascar,
but there are none in South America.

Thus existing fresh-water fishes point to an immediate connexion between
Africa and India, harmonizing with what we learn from Miocene mammalian
remains.

On the other hand, the Characinidae (a family of the physostomous fishes)
are found in Africa and South America, and not in India, and even its
component groups are so distributed,--namely, the _Tetragonopterina_[146]
and the _Hydrocyonina_.[147]

Again, we have similar phenomena in that almost exclusively fresh-water
group the Siluroids.

Thus the genera _Clarias_[148] and _Heterobranchus_[149] are found {147}
both in Africa and the East Indies. _Plotosus_ is found in Africa, India,
and Australia, and the species _P. anguillaris_[150] has been brought from
both China and Moreton Bay. Here, therefore, we have the same species in
two distinct geographical regions. It is however a coast fish, which,
though entering rivers, yet lives in the sea.

_Eutropius_[151] is an African genus, but _E. obtusirostris_ comes from
India. On the other hand, _Amiurus_ is a North American form; but one
species, _A. cantonensis_,[152] comes from China.

The genus _Galaxias_[153] has at least one species common to New Zealand
and South America, and one common to South America and Tasmania. In this
genus we thus have an absolutely and completely fresh-water form _of the
very same species_ distributed between different and distinct geographical
regions.

Of the lower fishes, a lamprey, _Mordacia mordax_,[154] is common to South
Australia and Chile; while another form of the same family, namely,
_Geotria chilensis_,[155] is found not only in South America and Australia,
but in New Zealand also. These fishes, however, probably pass part of their
lives in the sea.

We thus certainly have several species which _are_ common to the fresh
waters of distant continents, although it cannot be certainly affirmed that
they are exclusively and entirely fresh-water fishes throughout all their
lives except in the case of _Galaxias_.

Existing forms point to a close union between South America and Africa on
the one hand, and between South America, Australia, Tasman