436 MARINE INVERTEBRATES 



of a well-known Mediterranean pecten (P. jacobins), found com- 

 monly in Palestine, became an emblem of religious significance 

 during the middle ages. Returning crusaders fastened to their 

 garments a specimen of "St. James's shell" as an evidence of the 

 fact that they had been to the Holy Land, and the design of the 

 shell came to be adopted upon many coats of arms and also in the 

 insignia of various orders of devout and adventurous knights of 

 the middle ages. 



The animal is of the highest type of monomyarian mollusks, 

 that is, of bivalve mollusks with only a single adductor muscle. 

 Unlike most pelecypods, which have a very small foot, Pecten 

 rarely has a byssus, and is neither a stationary nor a sluggish crea- 

 ture. It can propel itself through the water by spasmodically clos- 

 ing and opening its valves, in an eccentric, darting sort of flight, 

 though most of the time it rests quietly upon the bottom. The 

 mantle is entirely open and highly ornate about its margin, 

 which is, furthermore, the seat of many eyes, capable, appa- 

 rently, of no mean degree of vision. The adductor muscle is very 

 large and strong, and occupies a central position, about which the 

 gills circle ; the latter are plainly filamentous. 



JP. magellanicus. The largest of the east-coast species of Pecten. 

 It is a Northern species, and was long known by the name of -P. tenu- 

 iscostattis a name given to it on account of its very numerous radiat- 

 ing striae ; but it was later discovered that the North Atlantic form Avas 

 in reality the same as the P. magellanicus of Patagonia. The latter being 

 the older name and entitled to priority, our shell became P. magellanicus, 

 the other name falling within its synonymy. The length and height of 

 this scallop are from five to five and a half inches. One valve is more 

 convex and slightly larger than the other, the smaller being lighter in 

 color. The valves gape considerably along their upper margin below 

 the hinge. The cartilage-pit is deep. North of Cape Ann this large 

 species is of common occurrence in moderately deep water. The deeper 

 bays and arms of the sea which everywhere penetrate the Maine coast 

 are its favorite resorts. A good way to catch pectens is to lower a fishing- 

 line at a spot where the fishermen report " scallop -ground," and drag it 

 along over the bottom. Sooner or later it will enter the open shell of 

 some pecten, which will instantly close its valves upon the string and 

 allow itself to be drawn out of the water. In Maine these large scallops 

 are eaten, but they have not found great favor in the city markets. In 

 color they vary from reddish through brown to ashen. 



P. tslandicus. A species not so large as the last, with more promi- 

 nently raised ribs (about fifty to one hundred in number), which are cov- 



