Some Effects of Frost

Abstract

Its fixation is effected simply by the foot disk acting as a I'ucker. When there is but one Sagartia upon a shell, it is found upon tbe ;;ide neare"t the crab. But there are oftpn several-as many as seven or eight-and then the foot disks, which touch each other without over lapping, cover nearly the entire shpl!. What are the relations of the crustacean and acti nia? Is it simply chance that causes them to live side by!<ide, one within and the other outside of the shell ? It is rather thought, and it is almost demonstrated ,