MOLLUSCS. 



261 



Pig. 271. —Flacuna sella. 



structure, a condition characteristic of the young of the higher forms. The foot is 

 small, and frequently spins a byssus, by which the animal attaches itself. 

 The typical genus of the 



family is Fecten, in which the 

 regular shell is usually ribbed, 

 the lines radiating from the 

 umbo. The anterior ears of 

 the shell are the larger. In 

 older times species of this 

 •genus were known as "pil- 

 grims' shells," from the fact 

 that for some unknown reason 

 the pilgrims of the middle ages 

 were wont to ornament their 

 clothing with these shells. So ■ 

 prevalent was the practice, 

 that when, in the early days of 

 science, it was adduced as a 

 proof of the biblical record of 

 the flood that fossil shells were 

 found in the Alps ; the reply was made by sceptics, that these were merely shells 

 dropped by pilgrims returning from Palestine. 



The common scallop of the southern shores of New England is known in scientific 



Fj)fM)wMiMm>ll!1|faiu mfr vwyr-iTro tcrmlnology as Pecten hyadians. It lives 



i ' '^mvA^^^^^: ilill """ ^l^^'lo'^ places, among the eel-grass, and 



\*^^^^^iM\^^hK|'I swims away at the slightest alarm. Thie 



y^f^^SSM^Stt^^^^^s^^^^ swimming, which is somewhat rare among 



bivalve molluscs, is effected by rapidly open- 

 ing and closing the valves of the shell, the 

 result being a sub-aquatic flight in a back- 

 ward direction. In color this species varies 

 considerably, but the flat valve is always 

 lighter than the other, being often white. 

 The other valve may be reddish, orange, 

 ])urplish, or mottled with two of these colors. 

 ^^^^^^^^^^^^^^^ The eyes, upon the edge of the mantle, are 



^B ^^^^^^K^^^^m^^S^^ silver or bluish, and are thu-ty or more in 



^K ^^ ^^^ ^H^^^^^P^ number. This is the scallop of the markets, 



FIG. 272.-P«c<™i„-adia«,, scallop. '^"'^ '* ^^g^^^^ P"^^"^ ^^ ^°™®' ^^''"SJh its 



sweetish taste makes it unpleasant to others, 

 while some find it actually unhealthy, and productive of nausea. Only the adductor 

 muscle is eaten. 



North of Cape Cod this species is replaced by two larger ones, P. islandicus and 

 P. tenuicostatus, neither of which are of much economic importance. In Europe the 

 scallop (P. maximus) and the quin (P. opercularis) are extensively eaten. Other 

 species, nearly two hundred in number, are found in all the seas of the world. 



In Lima the shell is obliquely oval, and gapes anteriorly. The hinge is straight, 

 toothless, and the ears are small. The border of the mantle is fringed with long cirri. 



