A HISTORY OF ESSEX 



The question of the food of the oysters in 

 different localities is one of great importance, 

 and may vary so much as to account for the 

 difference in flavour, and why they become 

 green in some localities and not in others, and 

 lose that colour when moved elsewhere. 

 This question of the food can be properly 

 studied only on the spot, by examining the 

 contents of the stomachs immediately after 

 the animals have been taken out of the water 

 in which they have lived, before the food has 

 been digested. 



Large numbers of the French oysters and 

 of the specifically distinct Portuguese and 

 American have been laid down in particular 

 localities. Mr. T. Newman, the manager of 

 the Colne fishery, informs me that the Portu- 

 guese have reproduced, though not in such a 

 manner as to be of commercial value ; but 

 the general temperature of the water is too 

 low for the successful reproduction of the 

 American or for that of the somewhat delicate 

 French variety of our native species, which 

 unfortunately for the same reason often fails 

 to arrive at maturity, to the great loss of those 

 interested in the fishery. 



4. Scrobicularia plana (Da Costa). 



Occurs in great numbers in Pye Fleet and 

 in some other estuaries. It is interesting to 

 keep it alive in an aquarium at the bottom of 

 which is a depth of 2 or 3 inches of mud, 

 and to see how it projects its longer syphon 

 to an extent of 5 inches and scoops up the 

 mud, which it swallows and afterwards ejects. 

 It may be killed with the syphons elongated 

 by keeping it in a vessel from which all air is 

 carefully excluded. 



5. Macoma balthica (Linn.). 



Common in the mud of the estuaries. I 

 have kept it alive in an aquarium with a mud 

 bottom and bred hundreds of small ones, so 

 that the surface of the mud seemed alive with 

 the protruded syphons. Some grew to be 

 \ inch in diameter in three or four months. 



6. Tellina tenuis (Da Costa) and 



7. Tellina fabula, Gronovius. 



These also occur, but are not so common 

 as Macoma balthica. 



8. Mactra stultorum, Linn. 



Not common but has been seen. 



9. Tapes aureus (Gmelin). 



This may be obtained alive from the mud 

 off Mersea when left dry at low water, being 

 fairly abundant. 



10. Cardium edule, Linn. 



Common in many localities. Some years 

 ago it was very abundant in the sandy mud 

 off Foulness, but living individuals were com- 

 paratively rare in 1894, after the previous 

 very severe winters. 



1 1 . Mya arenaria, Linn. 



This is very common in most of the estu- 

 aries, and judging from the great number of 

 dead shells in the living position it seems to 

 have been still more common in some locali- 

 ties than it now is. 



12. Mya truncata, Linn. 



Probably lives off Mersea since the shells of 

 recently dead individuals are not uncommon. 



13. Borneo Candida (Linn.). 



Abundant in Blakestone Hole near Bright- 

 lingsea and in the mud above Harwich. 



III. GASTROPODA PROSOBRANCHIA 



1. Gibbula cineraria (Linn.). 

 Common in various places. 



2. Littorina littorea (Linn.). 



This is so extremely abundant on the mud 

 flats left dry at low water that it must out- 

 number all other associated mollusca com- 

 bined. Many men and boys are employed in 

 collecting it for food. 



3. Littorina obtusata (Linn.). 



Found in sundry places, but not abun- 

 dantly. 



Rissoa and Zippora. 



These small shells are common in the 

 estuaries, and dead ones sometimes collect in 

 vast numbers on the shores. My specimens 

 seem to be chiefly 



4. Rissoa inctmspicua, Alder. 



5. Zippora membranacea, J. Adams. 

 Probably others could be found by careful 



searching. 



6. Buccinum undatum, Linn. 



This is more or less common all along the 

 coast and dredged at almost every station. 



7. Purpura lapillus (Linn.). 



This is commonly known as the 'dog 

 whelk,' and is collected and destroyed on 

 account of the damage it does in the oyster 

 grounds, by killing the animals. 



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