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and boring marine animals. 
is the part more directly acted upon, and which is depressed 
in the greatest degree. Hence the notch is always upper- 
most, and the Buccinum, when completely buried, is enabled 
to communicate with the water by its respiratory syphon. 
The Pholas can be observed to bore only in the young state. 
They are found completely buried, when so minute as to be 
almost invisible ; and the rapidity of their growth for the first 
few weeks, compels them to exert themselves perseveringly 
in effecting the enlargement of their habitation. Hence if a 
few of the young animals, which may be procured in abun- 
dance very early in the spring, are placed in a pan of water 
upon some of the substance which they had inhabited, they 
will, in a short time, begin to work, and continue to do so, at 
intervals, for two or three days ; thus affording ample oppor- 
tunity for observing the process. 
The only species of Pholas now found on these shores, and 
consequently, the only one whose habits I have had an oppor- 
tunity of observing, is P. Candida. It is, therefore, to this 
that my observations must be considered to apply more 
directly. 
The Pholas differs in many particulars from all other Bi- 
valves ; and its peculiarities of structure are so essentially 
connected with its method of boring, that a full description of 
them is necessary. 
From the syphonal, or posterior extremity of the valves, 
their dorsal edges are directed inward, till they meet at the 
hinge, whence they again separate ; and, finally, converge 
towards their points. There is, consequently, a triangular 
gape behind the hinge, which is lost by bringing the dorsal 
edges into contact ; and an egg-shaped one before it, which 
