330 FOSSIL OSTREID^ OF NORTH AMERICA. 



except the last one, are taken from spat which had fixed itself to and 

 grown on tiles placed in the water in the vicinity of Saint Jerome's 

 Creek, Maryland, during the summer of 1880. These tiles were placed 

 in position at determinate dates so that the age of this spat was ap- 

 proximately known. The figures are of the natural size. 



Some of the same lot of spat here figured was placed under favorable 

 conditions, and, in the space of twenty-two months from the date of the 

 fixation of the fry, had grown to a length of 3f inches, though the shell 

 was still comparatively thin. From this fact it is fair to infer that in 

 about twice that time, or in about four years from the egg, the oyster 

 is approximately adult and marketable. In their best condition they 

 are probably usually older than this, however. 



The notion that the oyster is not edible during the so-called unsea- 

 sonable months is not well founded ; they may in fact be eaten at any 

 season of the year, if fresh, withoutharm. In flavor, delicacy, and fatness 

 the oyster is not as good in summer as in the colder months, but beyond 

 this there is no great inferiority. The so-called fat of the oyster is not 

 the spawn or engorged reproductive organs, but the connective tissue, 

 indicated by c, in Fig. 3, Plate LXXIV. This connective tissue acquires a 

 peculiar creamy whiteness during the winter months, together with a very 

 considerable augmentation in volume, so that the mantle, especially that 

 portion covering the body, becomes very much thicker. In summer, on 

 the other hand, in consequence of the large amount of material which is 

 used up in the development of generative products, this same tissue 

 diminishes greatly in volume, and at the same time loses its creamy- 

 white appearance and becomes transparent or translucent. At the 

 same time, the minute structure of this same tissue acquires a some 

 what different character from that observed in the fat condition, becom 

 ing looser or more areolar in appearance as seen in thin sections. 



The waters in which oysters normally thrive are those where the bot 

 tom is pretty firmly fixed and not liable to sudden change. The crea 

 ture belongs to what is called the littoral or shore fauna, and I doubt 

 whether many extensive beds exist in waters more than 18 to 20 fath 

 oms in depth. The range of the American oyster, according to Verrill 

 is from " Florida and the northern shores of the Gulf of Mexico to 

 Massachusetts Bay ; local further north off Damariscotta, Me., and in 

 the northern part of the Gulf of Saint Lawrence, at Prince Edward 

 Island, in Northumberland Straits, and Bay of Chaleur. Not found 

 along the eastern shores of Maine, nor in the Bay of Fundy." In the 

 Chesapeake, where all the conditions are favorable, the oyster is found 

 more or less abundantly in the most of its tributaries, many of which 

 are estuarine. The " coves " or inlets in the Chesapeake are largely of 

 the same character and a re affected on account of their great width, in- 

 considerable length, and free connection with the bay, by the tide to 

 their very heads. In the great rivers, like the Potomac, which flow into 

 the bay the oyster beds are also extensive and important industrially. 



