Let us cilk, ill return, if it is not inconfiftent uith a 

 fvfteinatic arrangement, to defcribe the animal in one 

 ])lace as a Vermes Mollufca inhabiting a tube, and in ano- 

 ther place as a Vermes Tejlacea, or Sabella, inhabited bv 

 an Ampliitrite, or a Tcrehellx? Such, however, is the 

 cafe in fome modern fyftems,* and muft be where the 

 animal is capable of living independent of its cafe or co- 

 vering, and may fometimes be found deftitute of it in 

 perfeft vigour. 



Surely, it would have been a much more natural ar- 

 rangment, to have placed the Echinus in the order Tef- 

 Uicea, than the Sahella : indeed, fome authors have con- 

 sidered thefe as fhells ; but in the Linncean fyftem are 

 placed amongfl the mollufcous animals, though covered 

 with a fliell. 



-We (hall not, however, enter more largely on this fub- 

 je6l in a monographical work ; it is for thofe to confi- 

 der who write a general fyftem, whether the Sabella, 

 fhould not be expunged from the book of nature as a 

 fubftantive, and only defcribed with their feveral ani- 

 mals, with a view to fpecific diftinftions : and by fo do- 

 ing, all the cafes of larvce belonging to winged infefts, 

 which have been moft unaccountably intruded upon the 

 Tejlacea clafs, would naturally find their way to thofe 



Z z z 2 perfeft 



* Gmelin has defcribed Jmphi trite Auricoma in its proper place as a 

 mollufcous animal, and its cafe amongft the Tejlacea-, under the title of Sa- 

 })clla Belg'ua. 



