20 INTRODUCTION. 



before, furnished with lips, without teeth, and protruding 

 a clavated proboscis; feelers numerous, ciliated, capillary, 

 and placed round the mouth. This animal is an inhabi- 

 tant of many species of Dentalium, Serpula, and Sabella. 



Nereis. Body long, creeping, with numerous lateral 

 peduncles or feet on each side; feelers simple, rarely none; 

 eyes two or four, rarely none. According to some natu- 

 ralists, the Nereis inhabits some species of Sabella. 



Clio. Body oblong, natant, generally sheathed, and 

 furnished with two dilated membranaceous anns or wing- 

 like processes; tentacula three, besides two in the mouth. 

 According to some naturalists, the animal which inhabits 

 the Argonauta belongs to this genus. 



