ANNELIDS. 



65 



bearing the name of Serpula (Fig. 40). " If, while the con- 

 tained animals are alive, they be placed in a vessel of sea- 

 water, few spectacles are more pleasing than that which they 

 exhibit. The mouth of the tube 

 is first seen to open by the raising 

 of an exquisitely constructed door, 

 and then the creature cautiously 

 protrudes the anterior part of its 

 body, spreading out, at the same 

 time, two gorgeous fan-like ex- 

 pansions of a rich scarlet or purple 

 colour, which float elegantly in the 

 surrounding water, and serve as 

 branchial or breathing organs."* 



The minute convolutecl shells 

 (^ffpiroTbis), which are seen liiie 

 wliitish specks upon almost every 

 piece ofsea-weed,exhibit an instance 

 no less striking of the same exquisite 

 design, the same admirable adapta- 

 tion of means to the required end. 



The fourth tribe present, in their Fitr. 40-gkodp of sebpul^ 

 habits, a complete contrast to the last. They are formed for 

 locomotion, and some among them can swim with considerable 

 swiftness (Fig. 41). The roving life they lead has induced 



Hg. 41.— Nereis. 



Milne Edwards, the eminent naturalist, whose classification we 

 have followed, to bestow on them the characteristic appellation 

 of Errantes.\ 



' Jones's Natural History of Animals, page 313. 

 f Recherches pour Servir a I'Histoire Naturelle dn Littoral de la 

 France. Paris, 1834. 



Pakt i. E 



