XXXI 



The Nereis is faid to inhabit the Sabella; poflihly in 

 fome inftances this may hold good, but ^ve fufpecl the 

 greater part are independent in a moHufca flatc, inha- 

 biting the fand and mud at the bottom of the fea, where 

 they form themfelves cells ; and are much more aftive 

 than the other three preceding fpecies. 



Befides the animals here enumerated, there are doubt- 

 lefs many whofe habitations are teftaceous, which at pre- 

 fent are wholly unknown : that of the Nautilus feems to 

 be very imperfeftly underflood : it is figured in Riunpf. 

 Mus. tab. 17. fig. B. but no one appears as yet to have 

 arranged it, or even ventured to give it a name. 



It is moft probable, many of the minute flraight Nau- 

 tili are inhabited by animals very different from thofe of 

 the convoluted kinds. 



Some fpecies of Serpula, efpecially thofe of a conca- 

 merated flrufture, are doubtlefs inhabited by animals of 

 a different nature from thofe which refide in fhells of a 

 more fimple form. 



The Vcrmicula are probably inhabited by various ani- 

 mals, as their ftrufture is fo variable ; but it is likely vre 

 fliall ever remain in ignorant conjefture with refpe6l to 

 the conformation, and anatomical definition, of fuch di- 

 minutive creatures, fo obfcured by their teflaceous cc- 



vermg. 



MULLER'S 



