The Mussels and Rock-eaters 



The Hooked Mussel (M. hamaius, 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, i to 2 inches. ' 



Habitat. — Chesapeake Bay southward. Gulf coast. 



THE HORSE MUSSELS 

 Genus MODIOLA, Lam. 



Shell cylindrically oblong, inflated in front, with beaks 

 small, rounded, almost, but not quite terminal; epidermis often 

 produced into a beard-hke fringe ; byssus ample, fme. Animal 

 as in Mytilus; flesh orange or red. 



A widespread genus of seventy species, chiefly tropical, 

 includes the nest-builders of the family. Some cling in masses, 

 as Mytilus does. The coarseness of the flesh and its unfitness 

 for human food are indicated by the name. 



The Common Horse Mussel {M. Modiola, Linn.) is like 

 the edible mussel in outline, but the shell is much swollen, and 

 the beaks are not at the very end — a prolongation of the shell 

 extends farther in front. The valves are thick, and the glossy 

 brown epidermis wears a shaggy coat of hair, especially toward 

 the ventral posterior area. The flesh is orange-coloured, the 

 foot red. The moUusk harbours a little pea crab which is en- 

 tirely free from spines. Found in muddy gravel, from low water 

 to eighty fathoms depth. Or they hide in rock crevices, where 

 they are washed by the tide at high water. In mud the moUusk 

 stands vertical, its nose buried, its siphons up in the water. In 

 the region of Vancouver this "great horse mussel" grows to be 

 nine inches long and four inches wide. On northern coasts of 

 England it may attain an equal length, though the average is 

 about five inches. This is the size we commonly see it. 



Habitat. — Cape Hatteras northward, California to Alaska, 

 northern Europe. 



The Plaited Horse Mussel (A/, plicatula, Lam.) is narrowly 

 and triangularly oblong, gibbous, spreading and compressed 

 behind, plaited finely in radiating lines, especially strong over 



390 



