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, Lacep.) 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
