SCALLOP SHELLS. 57 



particular muscle, which is protruded through the gaping part 

 of the valves; they also adhere, when young, by means of 

 the bissiform epidermis, or bissus-like outer skin: this species 

 is a native of the Atlantic Ocean and the seas of Europe. 

 The Antique Ark, {A. antiqua,) is very like the Common 

 Cockle, being of a white colour, and heart-shaped. We give 

 below a representation of this shell, and also of the shell of 

 the pretty little Pearly Trigonia, (T. margaritacea,) included in 

 the Arcadce family; this is a rare species, found only in the 

 seas of New Holland. 



SCALLOP SHELLS. 



Several species of Scallop Shells are found scattered about 

 on our shores; they belong, as before stated, to the family 

 Pectinidce, the meaning of which term has been already 

 explained. These shells were called by Cuvier **the Putter- 

 flies of the Ocean," on account of the various and beautiful 

 colours which they exhibit. Some of them are exceedingly 

 thin, and brittle as glass; one species found in the Arctic 

 regions, is as transparent as that substance, and is therefore 

 called P. vitreus, from the Latin for glass, which is vitreiim. 

 One of the commonest of our native Scallops is the St. James' 

 Cockle, (P. JacohoPAis ;) this shell is found in great plenty along 

 our southern coasts; it is often referred to by old writers, 

 on account of having been commonly worn in the hats of 

 pilgrims to Palestine, or the Holy Land, as the scene of 

 our Saviour's life and death was called. Sir Walter Ealeigh, 



