Page:Natural History, Fishes.djvu/219

Rh zoologist makes two distinct Families. We prefer to consider them as Sub-families.

1. Pœciliana. In this group, the head is flat, the jaws are broad, and flattened horizontally, with a very small mouth, furnished with one or more rows of very fine teeth; the gill-openings are large, with, in general, five gill-rays; the body is rather short, and clothed with large, strong scales. This Sub-family comprises about fifty species, which chiefly inhabit the rivers of America. One little species is found in Sardinia, and another (Cyprinodon umbra, ) is remarkable as being one of the inhabitants of those subterraneous lakes in Austria where perpetual darkness reigns.

Another species, still more interesting, as if to make a superabundant use of the light which the former is destined never to see, has the organ of

vision fourfold. It is the Anableps tetrophthalmus, commonly known as the Four-eyed Loach of the Brazilian rivers. This appellation is, however, only partially correct. “The eyes,” observes Cuvier, “are prominent, placed under a