MOLLUSCA. 163 



deep, cast their spawn, and multiply -wonderfully. 

 It was soon found that it required only one year to 

 people a mussel-bed of considerable size, and that 

 one-tenth may be left to renew the bed completely 

 after the harvest. 



The mussels are taken from these beds from 

 July to October, and, though sold at a moderate 

 price, their commerce is not without importance, 

 many thousands of these mollusca being annually 

 dispatched from the coasts into the interior. 



After it had been discovered that a breed of 

 oysters might be crossed with other breeds, and 

 produce new varieties of oysters, similar experi- 

 ments were attempted with mussels, and have met 

 with considerable success, especially in Italy, and in 

 the Bay of Aisguillon, in France.* 



It has been found that the mussels, which live 

 suspended to piles, ropes of vessels, nets, etc., 

 attain to a much greater size than those which live 

 on the bottom, whether this be sandy, rocky, or 

 muddy. This fact has been turned to advantage by 

 the Italian and French mussel-breeders; thick 

 ropes, suspended to wooden piles, are placed in the 

 water of the mussel-beds, as represented in the 

 engraving ; the mussels adhere to these ropes by 

 their byssus, and the ropes are then tightened 



* D'Orbigny's " Hist, des Pares a Moules de I'Arrondisseinent 

 de la Eochelle," La Rochelle, 1847 ; and De Quatrefage's " Souv. 

 d'un Nat.," tome ii. p. 360, et seq. 



