A tuft of coarse, black hairs attaches the mussel to its sup port. A word as to its origin and use will answer a very natural curiosity which the sight of it always arouses. Nobody would guess that it is an organ of locomotion, but that is precisely what it is. The foot is a weak and flabby string of muscle, with a gland at its base, which when compressed throws out a spray of gelatinous substance which hardens into threads so strong as to sustain a heavy weight. The mussel may wish to climb up a pier. It has only to eject more threads upon a spot higher up than its original point of attachment, and as these harden, let go the old threads and hang on by the new ones. Pro gress by this method may not constitute a gait more speedy than the minute hand of a clock makes, yet it accomplishes all the mussel requires. Time is no object to him. I have tracked an individual by a fringe of cast-off threads, but I have never timed one. Though able by this means to be a free and inde pendent citizen, the mussel probably lingers near the place where it first settled down. It feeds like an oyster on what bounty the tides bring past the ciliated siphon tube. Bred in polluted water, it is often the carrier of disease germs when eaten. At spawning time it also causes sickness.
The shells are polished outside and made into needle-books, scent-bottle holders, pin-cushions, and various forms of jewelry, to sell to tourists and other souvenir hunters. The average shell is two or three inches long.
Habitat.— Europe. Arctic seas to Cape Hatteras, Pacific coast.
A variety, pellucidus, brightly rayed with green and yellow is often found with the typical form on our east coast. Another, var. glomeratus, thrives in San Francisco Bay. It is two inches long, and is constantly found in the fish markets of the city.
M. Californianus, Conr., is pictured by Reeve as a deeply grooved and rayed green and yellow shell when young, but at maturity a blue-black giant, rough, without stripes, and eight or nine inches long. It averages much smaller, and is brownish or purple, with orange flesh. The Californian Indians set sharpened points of this hard mussel shell in the tips of their harpoons.
389 The Mussels and Rock-eaters The Hooked Mussel (M. bamatus, Say) is a thick-shelled species with fine, crooked ridges, and a twisted, beak-like hook at the hinge end. Large clumps of the young are often found attached to oysters. It is dark drab or brown. Abundant in Florida. Length, 1 to 2 inches.
Habitat.— Chesapeake Bay southward, Gulf coast.