other species occur in other rivers of South-Western Asia, the Tigris, Euphrates, &c. Ten more are found in other parts of Syria, chiefly in the Damascus lakes, and the remaining sixteen species of the families Chromidæ, Cyprinodontidæ, and Cyprinidæ, are peculiar to the Jordan, its affluents, and its lakes. This analysis points at once to the close affinity of the Jordan with the rivers of Tropical Africa. The affinity is not only of species, but of genera, for Chromis and Hemichromis are peculiarly Ethiopian forms, while the other species are identical with, or very closely allied to, the fishes from other fresh waters of Syria. But the African forms are a very large proportion of the whole, and considering the difficulty of transportation in the case of fresh water fishes, the peculiarities of this portion of the fauna are of great significance.
"The fluviatile fishes claim special attention, dating, as they probably do, from the earliest time after the elevation of the country from the Eocene ocean. In the Foraminifera, mentioned above as found in the Dead Sea sand, such as Gr. capreolus, we have the relics of the inhabitants of that early sea. But of the living inhabitants we must place the Jordanic fishes as the very earliest, and these, we have seen, form a group far more distinct and divergent from that of the surrounding region than in any other class of existing life. During the epochs subsequent to the Eocene, owing to the unbroken isolation of the basin, there have been no opportunities for the introduction of new forms, nor for the further dispersion of the old ones. These forms, as we have seen, bear a striking affinity to those of the fresh-water lakes and rivers of Eastern Africa, even as far south as the Zambezi. But the affinity is in the identity of genera, Chromis and Hemichromis being exclusively African, while the species are rather representative than identical.
"The solution appears to be that during the Meiocene
