64 



Shell Life 



has a very deep sinus, showing that the siphons are 

 fully retracted. The animal is some^Yhat club shaped : 

 the siphons large, united nearly to the fringed 

 orifices, and covered by a sheath as in the Gapers ; 

 the foot also large, but short. They perforate, in 



rhdi 



(nat. size) 



shallow water, rocks, wood, and other substances that 

 are not so hard as their shells, making vertical 

 symmetrical burrows. Having made a burrow 



whether in limestone or in thick mud — the maker 



of it remains in it for life. This is very different 

 from the habits of ordinary burrowing mollusks. 



