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, Tasmania, and New Zealand on the other; but these unions were not synchronous any more than the unions indicated between India and Australia, China and Australia, China and North America, and India and Africa. Pleurodont lizards are such as have the teeth attached by their sides {148} to the inner surface of the jaw, in contradistinction to acrodont lizards, which have the bases of their teeth anchylosed to the summit of the margin of the jaw. Now pleurodont iguanian lizards abound in the South American region; but nowhere else, and are not as yet known to inhabit any part of the present continent of Africa. Yet pleurodont lizards, strange to say, are found in Madagascar. This is the more remarkable, inasmuch as we have no evidence yet of the existence in Madagascar of fresh-water fishes common to Africa and South America. [Illustration: INNER SIDE OF LOWER JAW OF PLEURODONT LIZARD. (Showing the teeth attached to the inner surface of its side.)]