274 LIFE BY THE SEASHORE. 



which are usually marked in shades of red and pink. We 

 shall consider in the order only three genera Pecten, Lima, 

 and Ostrea all characterised by the structure of the gills, 

 the absence of siphons, the single adductor muscle, and 

 some other common characters. 



Of the scallops the most abundant is the common scallop 

 (Peden opercularis), often seen in fishmongers' shops in the 

 larger towns. There are few stretches of sandy shore where 

 the separate valves of this species are not to be found, but 

 living animals are not quite so easily obtained. Those sent 

 to market are obtained by dredging, but where, as in the 

 Forth, there are large scallop beds, it is quite common to 

 find small living specimens on the shore rocks. After 

 storms, also, living scallops are often cast up in large 

 numbers on the shore, or are found living in the rock 

 pools. Such specimens are often somewhat injured by their 

 journey, and rarely live long in confinement, but small 

 specimens from the rocks live well, and form charming pets. 

 Select a few specimens about the size of a penny-piece, and 

 carry them home to your aquarium, or domicile them in 

 some rock pool. While you are admiring the beautifully 

 sculptured and coloured shell, its valves will suddenly gape, 

 and from the semicircular space so produced long, white 

 threads will be protruded, which float freely in the water. 

 Watch the opening shell carefully, taking care that your 

 shadow does not fall on the water, and you will see that the 

 two fringed mantle-folds are set round with jewels I would 

 say, did not strict accuracy compel me to call them simple 

 eyes. But jewels they are, nevertheless, if changing tint, 

 with gleam of emerald and amethyst, may earn the name. 

 It would not be easy to say how much the scallop really 

 sees with them, but it is certain that it very speedily becomes 

 aware of differences in the intensity of light, or of rapid 

 movement. When it is alarmed in this way, it suddenly 

 changes its position by flapping its valves together in a way 

 which drives it through the water in a series of rapid jerks. 

 This power of swimming is very characteristic of the 

 scallops, and is a very curious sight. As they rest in the 

 bottom of the pool or dish, they look as passive as any other 

 bivalve, and when without apparent stimulus of any kind 

 these passive shells suddenly spring upwards in the water, 



