In Brazil are to be found fishes, eellike in form, which burrow in the mud during seasons of drought. In wet weather this curious class of fish stores up in its system a reserve of fat, and then, when the dry season arrives and the rivers dry up, it constructs a deep tubular burrow, in which it doubles up, with head and tail together. The mouth of the burrow is closed with a most ingeniously constructed mud flap, through which are several small perforations, which permit the animal to breathe air directly, as it is also one of the few species gifted with both lungs and gills. While enclosed in its nest, the fish is frequently dug out by the natives, who highly prize its flesh. In the period of incubation it lives upon the reserve of fat accumulated during the rainy season. When the early rains soften the soil, the fish emerges from its burrow and resumes its aquatic existence.