214 



Dwellers of the Sea and Shore 



Another instance wherein the gills serve the double 

 purpose of supplying the animal with oxygen and food, 

 but in a manner considerably different, Is In the blood 

 worm {Polxcirrus eximius). It is a segmented worm, 

 deep crimson in color, and adorning its head is a crown 

 of crowded tentacles, or gills, composed of transparent 



serpula; a tube-building worm, this creature has built its tube on the 



dead shell of a whelk. 



filamentous strands that are continuously contracting 

 and expanding. These can be extended to several times 

 the length of the animal's body, the latter being about 

 three inches long. A pair of shorter, branched gills 

 also occur on each segment of the forward half of the 

 worm, while the hinder part is bare. In this creature, 

 as well as many others of Its class, the typical crown of 

 appendages that they bear may with equal correctness 



