250 MONOMYARIA.—AVICULADZ. 
coast, chiefly in deep water. Montagu found a bed 
of them in Salcomb Bay, which was occasionally 
accessible when the tide receded beyond its usual 
limits. The valves stood upright, with the broader 
PINNA. 
end about an inch above the surface, and the lower 
end fixed so firmly to the soil by a very large strong 
byssus two or three inches in length, composed of 
numerous fine silky fibres of a dark purplish brown 
hue, as to demand the exercise of considerable force 
for their removal. 
