[31 J FISHERIES OF THE UNITED STATES. 215 



auy single oysters of any class, but all grew in clusters of from three and 

 four to twelve and fifteen. The shells were clean and white, and free 

 from mud and sand. Generally there was found a tuft of red or white 

 sponge attached to the clusters, and the mature first and second class 

 oysters were covered and the interstices between them filled with those 

 of the third and fourth classes ; numbers of barnacles were also found, 

 and some crepidula, but tubicola were present only in small numbers. 



" The oysters found upon beds that have been much worked differ 

 materially, being single and broader in comparison to their length, round 

 and with blunt bills. They are usually dark in color, and have a con- 

 siderable amount of mud and sand on the shells. The sponges do not 

 appear to be as abundant, and the amount of dredging on any bed may 

 always be known by the appearance of the oysters brought up. Upon 

 an overdredged and almost exhausted bed the oysters will be large and 

 single, blunt-billed, with dirty shells, and with an almost entire absence 

 of sponges, barnacles, and crepidula; but the shells will be covered with 

 tubicola and bored in many places by the boring plioladL?* 



Aside from the effect of the dredge the growth of the oysters on a bed 

 is influenced by many other circumstances. First, the position and 

 character of the object to which the spat fixes itself have a large influ- 

 ence in shaping the form of the shell. 



The growth of the " bills " is always toward the surface of the water, 

 and by examining the series of specimens " of peculiar growth, due to 

 attachment of spat," many instances of the curious effect of this effort 

 of the animal will be noticed. During the early stages the shell grows 

 directly out from the beaks ; later, the tendency of the lower valve to 

 assume a convex form becomes more marked, and, should the animal be 

 so attached as to be in a horizontal position, this convexity of the lower 

 valve becomes vary prominent. If the attachment is such that the lips 

 of the valves are below the beaks, the shell will begin to take a lateral 

 twist, which will sometimes change the direction of shell-growth as much 

 as 90 degrees. Again, should the spat attach in large numbers to any 

 object and become much crowded, having no room for growth or devel- 

 opment, except vertically, then each individual shell will become long, 

 thin, narrow, and with very little convexity of the lower valve. Of 

 such description are the oysters growing on natural, undeveloped banks, 

 where they are found in enormous clusters, of from ten to fifty individ- 

 uals. Such oysters, more common on the Southern coast than the North- 

 ern, are called " cat-tongues " and " knife-blades " by the oystermen. 

 The " raccoon " oyster is also of somewhat similar growth and charac- 

 ter. 



After having developed to some extent in one locality or position, 

 if the oyster be removed to some other point, where" the conditions in- 

 fluencing its growth are changed, corresponding changes in the charac- 

 ter and growth of the shell may be expected. These changes are il- 



# Photographs of specimens are exhibited illustrating these differences. 



