Anableps

Anableps, a genus of Cyprinodonts, with three species, from tropical America. They are the largest fish of the family, being about a foot in length, and are remarkable from the position and structure of the eyes. The cornea is crossed by a dark horizontal stripe of the conjunctiva, dividing it into an upper and a lower portion, and the iris is perforated by two pupils. According to Dr. Gunther, this fish is frequently observed to swim with half of its head out of the water, in which position it can see as well as when below the surface.