CHAPTER XXXV: THE OYSTERS 



"Hech. sirs! but the month o' September's the month after my 

 ain heart — and worth ony ither two in the year — comin' upon you, as 

 it does, after May, June, July and August, wi' its R and its Eisters — 

 ilka shell as wide 's my loof — ilka fish like a shot-star — and the tottle 

 o the whole swimmin' in its ain sawt-sea liccor." — Nodes Ambrosiancs . 



Family OsTRy^iD/t 

 Genus OSTR^EA, Linn. 



Shell irregular, of unequal valves, the left one larger, con- 

 vex, and cemented to a support; hinge line thick, without teeth; 

 cartilage pad keeps valve open; animal without byssus, foot or 

 siphon; mantle with double fringed border, and "eye-spots"; 

 adductor muscle single, near centre of shell; heart in front of 

 rectum; gills four, concrescent with mantle. A single living 

 genus, with about fifty species, including the most important 

 of economic mollusks, the oysters of commerce. 



The Edible Oyster of Europe, (O. edidis, Linn.) is round 

 in outline when young, but it becomes very much distorted as 

 it grows. The concave left valve which is cemented to the sup- 

 port has marginal scallopings and shingled plaits or spines on the 

 surface. The flat or concave right valve is smooth, as a rule. 

 The individual is hermaphrodite, both male and female. Length, 

 3 to 6 inches. 



Habitat. — Europe. 



The Virginia Oyster (0. Virginica, Lister) is the North 

 American species whose cultivation centres in Chesapeake Bay. 

 Its form is irregular, elongated, with coarse, dingy exterior of 

 limy shell layers, and polished but not pearly lining. The scar 

 on each valve marks the place where the strong muscle is attached. 

 Sexes distinct. Length, 6 to 1 5 inches. 



Habitat.— Atlantic coast. 



Some authorities recognise a second, deeply scalloped species. 

 on northern shores, and designate it 0. borealis. In all proba- 

 bility it is but one form of the protean 0. Virginica. 



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