528 



THE SHORE SABELLA. 



into its tube the gills collapse and vanish, and the entrance of the tube is exactly closed by 

 the conical stopper. 



The Serpnla is a lovely inhabitant of the aquarium, but lias an inconvenient habit of dying, 

 sometimes coming out of the tube for that purpose, and sometimes retreating to its farthest 

 recesses, and there pu- 

 trefying, to the great 

 damage of the aqua- 

 rium. There are several 

 kinds of Serpula, some 

 of winch are only 

 attached by the lower 

 part of the tube, and 

 hold the rest of that 

 wonderful structure up- 

 right in the water ; 

 some, like the present 

 species, intertwine their 

 tubes very much like a 

 handful of boiled mac- 

 aroni ; while others, 

 such as the Serpula 

 triquetra, form tubes 

 which do not project at 

 all, but are affixed to 

 their supports through- 

 out their entire length. 

 This species makes a 

 triangular tube. There 

 are many interesting 

 circumstances connected with the habits and structure of these lovely worms, but our failing 

 space will not admit of a longer description. 



We now come to another pretty tube-inhabiting annelid, which is called Sabella, because 

 it lives in the sand and forms its tube of that substance. Several species of Sabella are found 

 on the European coasts, the most common of which is the Shore Sabella (Sabella alveolaria |, 

 a little creature seldom exceeding three-quarters of an inch in length. As is the case with 

 many of these worms, it has a thin tail-like appendage at the extremity of its body, which 

 is doubled up within the tube. The head is furnished with a great number of little thread- 

 like tentacles, which are very flexible, and under a good microscope are seen to have a groove 

 running along the centre, and a double row of teeth along the edges, something like the snout 

 of a saw-fish. 



This is a useful species to the naturalist on account of its plentiful occurrence, and readi- 

 ness to work while in captivity: If a Sabella be watched while it is building up its curious 

 tube, it will be seen to choose the particles of sand with the greatest care, selecting and seeming 

 to balance them with the tentacles, and cementing each in its place with a glutinous secretion, 

 which has the property of setting while under water. If the creature can be induced to build 

 its case against the side of a, glass vessel the possessor has cause to be gratified, for the creatine 

 does not waste material, and will often make the idass answer for one side of its tube, thereby 

 permitting the observer to watch its entire economy. 



The skin of these worms is very tough. I remember once having to dissect the digestive 

 organs for a lecture, and losing hour after hour in my endeavors to make a successful 

 preparation. Just as the lecturer' s servant came for the dissection, I had begun a fresh 

 subject, and quite lost patience. So I gave the worm an angry tug with the forceps, when 

 the whole skin of one side stripped off, leaving the digestive organs exposed as beautifully as 

 if they had been carefully dissected. 



SERPULA.— Serpula contortuplicata. 



