70 POPULAR BRITISH CONCHOLOGY. 



" On being placed in a vessel of sea-water, the valves of 

 the shell gradually opened to the extent represented in the 

 drawing. The feelers, or ciliated fringe of the upper orifice 

 of the mantle, moved slowly, as if in search of animalcules. 

 Having remained in this situation about ten minutes, water 

 was ejected with considerable force from the lower orifice, 

 which till now had remained motionless. The expulsion of 

 the water seemed to be effected by a sudden contraction of 

 the muscles, because this was never done without the valves 

 nearly closing at the same instant. After a few seconds 

 the valves gradually returned to their open position, and re- 

 mained quiescent as before till the water was again ejected 

 with a jerk. This alternating process was repeated at 

 unequal intervals during the whole time my specimens were 

 under examination, but at shorter intervals on receiving 

 fresh supplies of sea- water, when I suppose food (its quality 

 I could not ascertain) was more abundant. 



" The animal appears to be insensible both to sound and 

 light, as the presence or absence of either did not at all in- 

 terrupt its movements ; but its sense of feeling appeared to 

 be very delicate; minute substances being dropped into the 

 orifice of the mantle instantly excited the animal, and a 

 column of water strongly directed expelled from the shell. 



