forms a broad fold which falls over the brow, and furnishes an excellent protection for the eyes when the animal is digging in the banks of the streams. The nostrils are close to the end of the upper jaw. In the lower jaw, or rather in the lower part of the mouth, are a number of elevations and depressions which run from the interior of the mouth outward through the protecting skin, and serve, like similar features in the duck, to let the water run out of the mouth when the animal is eating in the thin mud. Within the mouth is a pouch in the cheek, which is used as a place for preserving food. Four horny teeth are set in each jaw, of which the front ones are long and narrow, the others oval and hollow-crowned. The eyes are small and brown, set close down by the bill, and look upward. The ear is entirely hidden under the skin, yet the animal hears very well. The fore feet have five long toes, much alike, with thick, rounded claws; the toes are connected by a skin which extends over the claws when the animal is swimming, but is drawn back when it is digging. The skin of the hind footFig. 3.—A, fore foot of the Ornithorhynchus; B, hind foot; a, spur. reaches only to the base of the claws. The males when grown have also a movable, sharp spur on the hind foot. The milk-glands are in the lower part of the body, but are not marked by any teats; the glands swell out on sucking, and the projection thus formed is seized by the broad, soft mouth of the young. It was formerly thought that the ornithorhynchus laid eggs; but it is now known that it brings its young alive into the world from a double uterus through the so-called urogenital canal. The animal chooses its abode in quiet places on rivers and ponds, where the large-leaved water-plants afford it sure concealment, and the steep, muddy banks allow it to dig deep holes, often fifty feet in length. It is extremely shy, cautious, and alert, and generally swims around under the water, only raising its head for breath, but seldom high enough to be shot at. The young, born about the beginning of December, are put by the mother in a nest which she has prepared at the end of the burrow, and has lined with dry grass. They may be caught by digging them out. They do very well in an aquarium, and make comical, playful pets. The grown animals sleep through most of the day rolled up into a ball, but are lively at night. When free, they