1t4 
before us. There has been found by sir. Gerville, at 
Golleville, and several other places near Valognes, a 
gaping shell, in many of the casts of which there are 
also similar furrows, but still less constant and less 
regular. The inconstancy of the furrows in these would 
lead us to suspect they arise from some disease or acci- 
dent attending the growth or situation of the shell, 
similar perhaps to the formation of pearls, 
