70 



the shell of the animal itself. Hence some have 

 supposed, that they were hatched in holes acci- 

 dentally formed in stones, and that they na- 

 turally grew of such a shape as was necessary to 

 fill the cavity. 



The holes in which these insects lodge are 

 usually twice as deep, at least, as the shells are 

 long : the figure of the holes is that of a trun- 

 cated cone, excepting that they are terminated 

 at the bottom by a rounded cavity, and their 

 position is usually somewhat oblique to the hori- 

 zon. The openings of these holes are what be- 

 tray the Phloas being in the stone ; but they are 

 always very small in proportion to the size of the 

 fish. There seems to be no progressive motion 

 of any animal in nature so slow as that of the 

 Phloas ; it is immersed in the hole, and has no 

 movement except a small one towards the centre 

 of the earth ; and this is only proportioned to 

 the growth of the animal. Its work is very dif- 

 ficult in its motion; but it has great time to per- 

 form it in, as it only moves downwards, sinking 

 itself deeper in the stone as it increases in 

 bulk. That part, by means of which it perform 8 

 this, is a fleshy substance, placed near the lower 

 extremity of the shell ; it is of the shape of a 



