The Purples. Dog Winkles 



culated; columella broad, flat, orange-red; aperture orange; lip 

 margin ridged. Length 2^ to 5 inches. 



Habitat. — Philippines. 



The large species were commercially important in the earliest 

 times because they yielded more of the precious dye than the 

 smaller kinds. 



The Rock Purple or Dog Winkle (P. lapillus, Linn.) is one 

 of the best known inhabitants of northern rocky coasts on both 

 sides of the Atlantic. P. saxicola, Val., of the west coast, is probably 

 the same. This species has attained its remarkable geographical 

 range by variations which adapt it to changed conditions of life. 



The collection of P. lapillus made by Cooke in Great Britain 

 alone exhibits nineteen distinct forms. Large size, prolonged 

 spire and small mouth characterise those found on protected coasts 

 where food is plenty and attachment to the rocks an easy matter. 

 A low spire, a large mouth, small size and a thick shell belong to 

 forms taken in exposed situations where food is scarce. The most 

 strikingly banded and brightly coloured shells are found on veined 

 and coloured rocks, the dullest in estuaries and sheltered bays. 



Linnaeus called this species by a name which means "pebble": 

 doubtless he saw, as they lay exposed by low tide, the resemblance 

 of these numerous shells to the pebbles on the beach, and saw in 

 that resemblance a reason for the success of the species in the 

 struggle for existence. They share with pebbles the hard knocks 

 all shore-dwelling mollusks get when the sea is rough. The 

 American forms are rarely over an inch long. In England they 

 range upward to two inches, and over, in favourable situations. 



The colouring varies from whitish through all the yellows 

 and browns, bright and dingy, to dark red. The surface may 

 be smooth or finely cancellated or beset with tubercles. The 

 roughest specimens in Dr. Cooke's series came from the oyster 

 beds, six fathoms deep. 



The activities of this purple are well known. He shambles 

 about clumsily, or sits faithfully plying his drill. He is cordially 

 hated by fellow pensioners on the bounty of the sea. He eats 

 oysters and mussels, thrusting the long proboscis into the hole 

 laboriously drilled through one of the valves, and sucking out 

 the contents. Mytilis edulis, the edible mussel, is his favourite 

 food. Lacking this delicacy, he will bore the shells of limpets 

 and barnacles — even pick the bones of dead fish and crabs. 



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