374 LITTORINID^. 



the " periwincles " on our northern coasts ; he figured 

 a specimen in his Natural history patchwork the 

 " Gazophylacium," with a note that it came from the 

 Orkneys, and "resembles our Scarborow covins, but 

 four times bigger." Many from Shetland are an inch 

 and three-quarters long. Males are narrower and 

 smoother than the females, and have a contracted 

 mouth. The operculum is often irregularly laminated. 

 Mr. Rich found one that was double, the original oper- 

 culum only being spiral. The animal is sometimes in- 

 fested by Trematode parasites. M. Lespes detected 

 Cercaria proximo, in the liver, and C. Iwearis in the 

 kidney of L. litorea at Arcachon. Man has utilized peri- 

 winkles as well as everything else in creation. They are 

 employed by some of the Essex oyster merchants to keep 

 the grounds clear of seaweeds ; Mr. Smith of Burnham 

 informs me that he lays down every year scores of 

 bushels for that purpose. They are also very serviceable 

 in the same way for cleaning an aquarium. The peri- 

 winkle is a favourite delicacy of the poor. Dray ton, of 

 course, did not omit it in his catalogue of our edible 

 mollusca. According to- Swammerdam, it was eaten in 

 Holland during the months of April and May only ; it 

 was said to excite thirst. In Mr. Hyndman's Report 

 to the British Association on the operations of the 

 Dredging Committee at Belfast (1857) we find that at 

 that place " the periwinkles are gathered and exported 

 in large quantities to London. Mr. Getty, Secretary 

 to the Harbour Commissioners, informs me that this 

 trade has been carried on for the last twenty-five years 

 by one person, who employs three horses and a mule to 

 draw them, besides employing boats, &c., paying about 

 j60 weekly in wages during the season. The peri- 

 winkles are assorted and put into sacks, of which one 



