134 



INVERTEBRATE ANIMALS. 



which is provided with eyes and with two or more feelers, which 

 differ from the anteniue of Insects and Crustaceans in not being 

 jointed. The mouth is placed on the inferior siirface of the head, 

 and is sometimes fui'nished with one or more pairs of horny jaws 

 which work from side to side. The \ipper part of the alimentary 

 canal is muscular, and can be turned inside out, or protruded beyond 

 the true opening of the mouth. The pseudohtemal system is well 

 developed, and its contained fluid is mostly red. Eespiration is 



Fig. S5. — Cirrliatulus 



an " Errant Annelicle," in its living condition. 

 (After Venill.) 



effected by external processes, gills or branchife, arranged in tufts 

 placed along the sides or back of the body, and not confined to 

 the immediate neighbourhood of the head, as in Tuhicola. The 

 sexes are in different individuals, and the young pass through a 

 metamorphosis. 



Amongst the best known and commonest of the TJrrant Annelides 

 are the conmion Lob- worm {Arcnicola piscatorum) ; the Sea-centi- 



