North American beaver large, webbed hind feet. The unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane which allows the beaver to see under water. The nostrils and ears are sealed while submerged. A thick layer of fat under its skin insulates the beaver from its coldwater environment. The beaver's fur consists of long, coarse outer hairs and short, fine inner hairs (see Double coat). The fur has a range of colors, but usually is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur.
Castor and Pollux (Prado) Castor and Pollux (Prado) The Castor and Pollux group (also known as the San Ildefonso Group, after San Ildefonso in Segovia, Spain, the location of the palace of La Granja at which it was kept until 1839) is an ancient Roman sculptural group of the 1st century AD, now in the Museo del Prado, Madrid. Drawing on 5th- and 4th-century BC Greek sculptures in the Praxitelean tradition, such as the Apollo Sauroctonos and the "Westmacott Ephebe", and without copying any single known Greek sculpture, it shows two idealised nude youths, both wearing laurel wreaths. The young men lean against each