CROUCH : CREPIDTJLA. 19 



OX THE OCCURRENCE OF CREPIDULA FOENICATA IN ESSEX. 

 By Walter Croijch, F.Z.S. 



Read July lifh, 1893. 



On the 6tli September, 1891, when collecting at Stone Point, St. 

 ,Osyth, on the river Colne, I found a broken piece of oyster-shell to 

 which was attached a dead specimen of C. fornicata. This form is 

 common enough on the east coast of North America, but I had never 

 seen any record of its occurrence on our shores. On enquiry I ascer- 

 tained that young American oysters had been laid down to fatten in 

 this locality, and concluded that this non-European shell had been 

 thus introduced. I thought it well, however, to record the fact in 

 the "Essex Naturalist," December, 1891. 



On the 4th March, 1893, 1 received a small parcel of marine 

 objects from the river Crouch, over 16 miles from the first mentioned 

 locality, taken by one of our trawling companions, John Bacon, whilst 

 engaged in the oyster fishery, on board a Burnham smack ; and 

 amongst these was a living example of this species, which in his letter 

 to me he called " a crow- oyster on a stone." 



In reply to my request for further information he told me that he 

 had seen these in different parts of the Crouch and Roach rivers, and 

 remembered them for 15 or 20 years ; but that they were scarce ; and 

 that he had never heard pf any American spat or young oysters being 

 placed in any of these layings. 



In April he found two more living specimens on oysters at the ferry 

 layings, Cricksea. One of these he sent to me on the 1 5th April ; it died 

 a few hours after, but I showed the shell with the animal still in it to 

 Mr. Edgar A. Smith the next day. The shell is very concave, and 

 rich in colour inside, the septum being enamel- white. 



The soft parts of the other specimen were not preserved, but the 

 shell given to me later on by Mr. E. A. Fitch is much flatter and 

 larger, and the internal colour is more mottled. 



All these shells exhibit considerable variability in size, shape, and 

 colouring, but compare with specimens from North America. 



The live oysters on which these latter specimens were found are 

 not natives^ but French oysters laid down when a year old. 



[Since the above was read, Mr. H. Wallis Kew has kindly drawn 

 my attention to the (Yorkshire) "Naturalist," 1888, p. 275; wherein 

 Mr. Arthur Smith records the occurrence of dead shells on the beach 

 at Grimsby in 1887-8 ; and says they are often found adhering to the 

 shells of oysters brought from America, and laid down at Clecthorpc. 



This is again mentioned by Mr. Kew in his " Shells of the Lincoln- 

 shire Coast," Nat. 1889, pp. 358-9.] 



