ANNELIDES, OR RED-BLOODED WORMS. 159 



at the anterior end of the body ; and these have been 

 supposed to be eyes, though no proof of their being 

 organs of vision has been discovered. There is but 

 one aperture, which serves the place both of moiith 

 and vent. This communicates with a much-branched 

 stomach, where the food is received and digested ; and 

 the undigested matter is rejected by being driven back 

 by the way through which it came. Besides this diges- 

 tive apparatus, there is a rudimentary vascular system, 

 consisting of a delicate network of vessels ramifying 

 through the body. Such is the simple arrangement of 

 parts in these animals. They were formerly placed near 

 the Leeches, which are of a much higher type of struc- 

 ture, though externally somewhat similar ; but they are 

 now arranged with the intestinal worms, to which their 

 structure nearly allies them. None of the Planarice, 

 however, are found in the bodies of other animals. 



A considerable number of the class of ANNELIDES the 

 group to which the Common Earth- Worm and the Leech 

 belong are natives of the sea, and many of them are 

 objects of great beauty. Some are curious in their 

 structure : and others, equally curious and beautiful, are 

 sought after by fishermen to be used as bait. All these 

 animals have so much general resemblance to each 

 other, that it requires little observation to recognise any 

 as belonging to the group, when you are once familiar 

 with any member of it. They are all of a long, gene- 

 rally a worm-like form, capable of contracting conside- 

 rably in length, and of extending the body again. The 

 body is composed of a set of rings or joints, connected 

 by a common flexible skin or covering ; and every 

 joint except the first, which serves as a head, and the 



