26 



XATTKAL BANKS. 



During my stay at St. Jerome's creek. I examined the 

 natural oyster banks which were readily accessible in 

 shallow water, with gratifying results as to the habits of 

 the animal under virtually undisturbed conditions. — 

 These banks, like those of Europe, always appear to be 

 much longer than wide, but many of them are almost 

 entirely exposed to the air during low tide, a rare occur- 

 rence, according to Mobius, with the banks on the Schles- 

 wig-Holstein coast of the North Sea. I learned from the 

 owners of some of these banks that, although a consider- 

 able projjortion of the oysters on them were at times 

 fi-ozen to death during the severe winters, that the fecun- 

 dity of those which remained was such, combined ^vith 

 the naturally favorable conditions found on the banks 

 for the growth of old and young, as to restore the beds 

 to their wonted productiveness in one or two seasons. 

 Whether this description of the fecundity of the beds 

 found in shallow water is overdrawn or not matters little, 

 since there was the plainest evidence that we had here 

 before our eyes the best natural conditions for the propa- 

 gation and feeding of the individuals. These beds are, 

 in a word, natural spat collecting grounds : places where 

 such conditions obtain as will allow a large proj^ortion of 

 the swarming brood of the sj^awning season to affix itself 

 securely and survive in i30sitions where an abundance of 

 food may be got. The tide ebbing and flowing over the 

 beds not only carries with it in suspension the microsco- 

 pic food best adapted for the nourishment of the oysters, 

 but also tends, owing to the peculiar arrangement of the 

 shells on the banks, to keep the surface of the latter 

 clean, so as to be Avell adapted as favorable points of at- 

 tachment for the young. 



The oysters assume an approximately vertical position, 

 as sho^^^l in the cross-section Fig. 3, of a bank in St. 

 Jerome' s Creek owned by Mr. J. W. Wrightson. The 

 assumption of this position seems perfectly natural ; 



