92 POPULAR BRITISH CONCHOLOGY. 



mentioning. Some suppose that the pearls are sent abroad 



to be manufactured into seed-pearls ; others, more gravely, 



that they are exported to India to be dissolved in the sherbet 



of the Nabobs." 



Who knows but that another ' buckler * may be preparing, 



to grace the triumphs of another Ccesar, who modernizes the 



title by a different mode of spelHng ! 



II. Dreissena poli/morjjha has recently been introduced 

 into this country, and is a naturalized mollusc. The 

 shell is very angular, and is painted with zigzag mark- 

 ings. Inside it has a kind of plate, or septum, across 

 the beaks. It was first noticed in the Commercial 

 Docks, attached in abundance to shells and timber, by 

 my relative, Mr. J. Bryant, who used the animal as 

 bait for perch. The animal differs from Mytilus in 

 having the mantle closed : it propagates rapidly, and is 

 now common. It is difficult to account for its intro- 

 duction into our river ; for, on the supposition that it 

 came attached by its byssus to the bottoms of ships, it 

 must have passed through miles of salt water, and if it 

 came on timber from Wisbeach, as believed to be the 

 case, it must have lived during the journey without 

 water. Whatever might have been the perils and dis- 



