D E N T A L 1 U M. 1 09 



as in other genera, is attached. It is true, that 

 both in this and the following genus the aniraal 

 does not appear to be restrained in his motions 

 within the limits of his house ; but it by no means 

 follows that he has not some tie to prevent his 

 leaving it. Were he perfectly at liberty, the-form 

 of his receptacle would scarcely preclude the action 

 of the water or accidental violence from forcing 

 't'lm from it, against his will. 



