THE MOLLUSCA 195 



opening and smart closing of the shell, this causing a rapid 

 expulsion of water, which, reacting on the pecten, drives it 

 backwards. The edges of the mantle are fringed, and bear 

 well-developed eyes, usually sixty or seventy in number. 

 These may be seen when the shell is slightly opened, as a 

 double row of brilliant green beads, about the size of a small 

 pin's head. Microscopic sections of these eyes show a 

 very high development. The shell is beautifully con- 

 voluted, in radiating, fanlike pattern. The valves are 

 unequal, the right one being flat, the left convex. Full- 

 grown specimens measures five inches across. 



Other species are : 



Pecten opercularis (the "Queen Scallop"). This one is 

 equally common, and occurs in " beds " close inshore and 

 extending to deep water. Both valves are convex, and 

 more finely convoluted than in the last. It measures two 

 inches in diameter. 



Pecten varius. This is a smaller species, about an inch 

 across, both valves equal, but the wide, hinged portion, 

 which in the foregoing is straight, is developed more strongly 

 on one side (see Photo). The colours in this species are 

 very varied and beautiful. Specimens occur of a pure 

 white, others lemon-coloured, crimson, brown, but the 

 majority are mottled red and white. 



This one attaches, by a little bunch of horny fibre, the 

 byssus, to stones or to others of its kind, forming bunches. 

 It is sometimes dredged for market. There are several 

 other species on our shores e.g. Pecten pusio, P. tigrinus, 

 etc., but these are rare. 



Allied to the pectens are : 



Lima hians. This is a very beautiful form ; the shells 

 are elongated, finely convoluted, and pure white. The 

 mantle is divided at its edges into a Ions; fringe, which can 

 be extended considerably beyond the margins of the shell. 

 These fringes are of bright colour, usually bright red and 



