196 
THE ESSEX NATURALIST. 
I owe to the courtesy of Dr. C. T. Trechmann the loan of a 
fine specimen (plate xii., fig. 3), dug up in Hartlepool Harbour at 
8 feet depth in sandy clay, measuring 4 by 4J inches, with a com¬ 
bined depth of 2 inches. This example exhibits the yearly accre¬ 
tion of surface, there being about 40 growth lines in each valve. 
Jeffreys’ shell was evidently an aged example, and my own 
impression is that any healthy and well-nourished oyster, 
enjoying a quiet life in deep water amidst congenial surroundings 
may develop into the hippopus state. How long an oyster 
lives is uncertain. Prof. Moebius states that, although rarely 
met with, he had seen specimens between 25 and 30 years old, 
but if thickness and number of layers is any criterion, they 
certainly live to a more advanced age than that. 
Deep-sea, or “trawlled” oysters range from the Varne and 
Ridge Shoals in the English Channel to Burnham, in Norfolk, and 
the North Sea, and are a rugged type of shell, averaging 4 by 3J 
inches of good size. Shells from near the Dogger are usually 
very irregular in outline, undulated in every direction with 
numerous excrescences. They are long in proportion to breadth, 
and deep. One in my collection, 5 by 3J inches, has a depth of 
if inches in the very convex under valve. 
Lamarck located his species from Boulogne to La Manche, 
and Dautzenberg et Durouchoux ( Feuille . des Jeun. Nat., 1914, 
vol. 44, p. 48,), say that the young shells they found affixed 
to rocks and stones in the Bay of St. Malo, probably belong to 
the hippopus distinguished by “ ses cotes rayonnantes nombreuses 
et saillantes.” Various forms have been associated with the name 
hippopus by Messrs. Praeger, Marshall, and the Roussillon 
authorities. 
Lamarck specially notices that 0 . hippopus is not so good tO' 
eat nor so digestible as 0 . edulis, but whether this is a test of 
specific value has yet to be decided. Gastronomes of all periods 
have noted this variation of flavours, from the days of Juvenal 
onwards. Walfleet near Colchester was noted as early as- 
1622. Drayton (Polyolbion) writes of them “ Think you our 
oysters here unworthy of your praise.” T. Flatman, 1674. 
(Belly Gods) thought so, apparently—“ Your Wall Fleet oysters, 
no man will prefer before the juicy grass-green Colchester.” 
Most of the oysters sold at Stourbridge fair, near Cambridge, seem 
to have been of this type, as it is recorded in Hone’s Everyday 
