HARDWICKE'S SCIENCE-GOSSIP. 



i8i 



three long, round, pinkish, almost smooth tubes about 

 a quarter of an inch in diameter, twisted together 

 slightly, and incrusted with sponges, &c. This is 

 S. coiitortiiplicata (Cuv.). At the entrance of the 

 tube we observe a neatly-made circular structure of a 

 turlcey red colour, and serving the purpose of a door. 

 AVhen the shell is popped into a jar of sea-water in a 

 dark situation, tliis membranous cover or operculum 

 is seen to be pushed forth, and a fan-shaped expan- 

 sion stealthily emerges, consisting of two large scarlet 

 tufts of about thirty filaments, each furnished with 

 arge and energetic cilia. These are the gills of the 



lets. S. triqnetra (Mont.) is another species which is- 

 found in considerable profusion adherent to shells, 

 stones, &c. Its tube bears a sharp keel all along its- 

 length, and a knob above the aperture ; the oper- 

 culum is calcareous and conical, and fixed between 

 two soft processes of its stalk ; the gills have about 

 eight filaments in each tuft ; the bristles are similar 

 in shape to the last species, but I am unaware of any 

 hairs or toothlets having ever been detected at their 

 extremity ; the hooks are broader and more triangular 

 than those of .5". contortiipUcata, and are cut into 

 about nine teeth, and there are no mop-like bristles.. 





fM^. 



Fig. lO-j.^Saiella unisj>ira. 



Fig. log.— Terebella. 



Fig. 110.— AjHphitrite 

 veiitilabruiu. 



Fig. 



•Various forms of hooks {tincini) used by the Tubicolor anneltda. 



animal, and right vigorously do they operate as 

 aerators of the true blood (not the peritoneal fluid). 

 The body is divided into a great number of segments ; 

 the upper branch of the feet carries a number of 

 bristles which are long and acicular, and when viewed 

 under high powers are seen to be fringed at the 

 extremity with a series of very fine hairs or toothlets ; 

 on the lower branch of the feet there is a singularly 

 curious ribbon or string of bent hooks, each cut at 

 the edge into five teeth ; there is also a third set of 

 bristles of a mop-like shape, the broad flat end being 

 cut into a series of beautifully fine and delicate tooth- 



S. vermicidaris is a third species which construzts- 

 a cylindrical tube without a keel, and with a plain 

 aperture ; the operculum is a very elegant structure, 

 having a double funliel, a shallow one planted above 

 another deeper one, both being neatly sliced on the 

 rims into a number of saw-like teeth ; the branchi^ 

 have numerous filaments in each tuft, and the bristles 

 and hooks are of similar structure to the last, differ- 

 ing only slightly in shape and in the number of 

 teeth. 



The function of these beautiful hooks and bristles 

 in the tube-tenanting sea-worms may be indicated as 



