nearly allied to fome parts of the clafs Zoopliyta than to 

 that of Tejlacca. To tlie tjeiius Tuhularia leveral mighi be 

 added with more propj'iety ; or perliaps if they were only 

 noied in Helminthology as fubfei vient to the knowledge of 

 "the animal, and an afiiftant to its fpecitic dilHnc^tion,, it would 

 be tnoll conducive to a more perfect natural fyftem. Our 

 countrvnian the immortal Ellis did notfcruple to clafs the 

 Sabella alveolata, and penicillus aujongfl his Zoophyta, as 

 lubularia ; and Muller has followed the example. How- 

 ever they do not Itridlly belong to that genus, nor indeed to 

 any other ; fo that fluuld they be removed into that clafs by 

 thofe who prefer making the cafe or tube the fubftantive 

 inftead of the animal, they n^uft conlUtute a feparate genus. 



When the great Linnaeus rejedled the Echinus from the 

 conchological j)art of his fyftem, it was not probably from 

 any comparative view of the fubllances chemically analyzed^ 

 or he would no more have placed the meinbranaceo s cafes 

 termed Sabella amongfl fliells, than he would have included 

 the Echinus. The detection of phofp/jafe of lime in the cover- 

 ing of Echini certainly diftinguifhes them from teftaceous 

 fubllances, which contain only carbonate of lime, mixed with 

 animal gluten. 



By this natural confiitution of the compone'^t parts of 

 animals, is the Sabella detached from either the above, being 

 in all probability dellitute of either /)/zoy/j/ja/^ or caibonaie o£ 

 lime, if diveiled of ail extraneous matter. 



APPENDIX. 



