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 their cousins' herd. Idas and Lynceus eventually set out for home, leaving Helen alone with Paris, who then kidnapped her. Thus, the four cousins helped set into motion the events that gave rise to the Trojan War. Meanwhile, Castor and Pollux had reached their destination. Castor climbed a tree to keep a watch as Pollux began to free the cattle. Far away, Idas and Lynceus approached. Lynceus, named for the lynx because he could see in the dark, spied Castor hiding in the tree. Idas and Lynceus immediately understood what was happening. Idas, furious, ambushed Castor, fatally wounding him with