110 LIFE BY THE SEASHORE. 



are absent. As compared with any of the preceding worms 

 the parapodia are reduced, and only project slightly at the 

 sides of the body. Both the common species inhabit muddy 

 sand, and both are extraordinarily brittle, breaking into 

 pieces on the slightest provocation. Common as the worms 

 are it is in consequence very difficult to get a complete 

 specimen. The gills (dorsal cirri) are carried curved over 

 the back, and being filled with red blood are in life very 

 conspicuous objects. The tentacular cirri are broad and 

 long, and in life are in constant movement. Like other 

 parts of the body these are very apt to be thrown off by 

 captive specimens. There is little difficulty in distinguish- 

 ing between the two species. The larger, N. coniocephala, 

 is said to attain a length of eight inches, but on the 

 East Coast at least is usually much smaller; the smaller, 

 .ZV. vulgaris, is three to four inches long. The larger is the 

 handsomer species, for it is usually of a fine green colour, 

 which contrasts with the scarlet gills. In Nerine vulgaris 

 the body is usually yellowish red, but also exhibits a ten- 

 dency to become green. It will be noticed that the surface 

 of the gills is increased by a membrane (the podal mem- 

 brane) which extends up the gill, its size differing in the 

 two species. The other distinguishing characters are given 

 at the end of the chapter. 



In Nerine the parapodia project slightly at the sides of 

 the body, but in the remaining worms they are at most 

 represented by small tubercles bearing the bristles. The 

 worms are almost either burrowers or tube-formers, and 

 very frequently the anterior end, which projects from the 

 tube or burrow, differs markedly from the posterior. 



The first of these worms which we shall consider is 

 recommended by its great abundance on the shore rather 

 than by any beauty or great interest. In turning over 

 stones on the rocks, the beginner often tries stones firmly 

 bedded into mud or sand, and therefore without any under- 

 lying cavity. When such stones finally yield to a strong 

 pull, they reveal an odorous substratum of mud which is 

 usually traversed in all directions by slender scarlet threads 

 moving about like living worms. A little investigation will 

 show that these are the tentacular filaments and gills of a 

 reddish worm embedded in the mud. If molested the 



