530 



Some are compofed wholly of fmall fiiells of various 

 kinds; others of fragments of (liells mixed with fand, 

 bits of flick, flalks or fibres of plants ; and it is remark- 

 able, that forae fpecies attach pieces of flick longitudi- 

 nally, while others bite off fhort pieces and place them 

 tranfverfe, like bafl^et-work, fome placing them trian- 

 gular, others quadrangular, or lozenge-fliaped. But 

 the mofl beautiful variety, is that found in waters a- 

 bounding with Helix vautileus, with which we have 

 feen thefe cafes compleatly coated in a regular and mofl 

 elegant manner, with their apertures outwards, and fome 

 of the animals yet alive. Another variety, coated with 

 fine fand, and minute bits of fliining mica, found in Corn- 

 wall, and other flreams running over micaceous granite, 

 is deferving notice : but we mufl not enter further on a 

 fubjeft which more properly belongs to Entomology. 



Why a part of the Linnccan Sahcllce fliould be removed 

 into the Mollufca clafs o^ Vermes, and others leftamongfl 

 the Tc/lTcea is difficult to determine ; for thofe whofe in- 

 habitants are Nereis, have no more claim to a place a- 

 mongtt fhells, than fuch as are inhabited by an Amphi- 

 trite, or Terebella; and might certainly, with as much 

 propriety, be transferred to their proper animal clafs. 



That the Sahclla genus fliould be wholly expunged, 

 and the feveral animals placed in their refpeftive gene- 

 ra amongfl the Mollufca, there can be no doubt ; for 

 ihofe, whofe cafes are made up of agglutinated frag- 

 ments 



