5 



POPULAR SCIENCE MONTHLY. 



The Noah's ark is a most oddly shaped shell, and was named 

 by Linnaeus from its resemblance to that primitive craft. One 

 ark found in the Mediterranean sometimes contains violet-colored 

 pearls, and one on our coasts is called the " bloody clam," from its 

 fiery gills and the crimson fluid in its tissues. Some of the arks 

 live in submerged clefts of the rocks, and are so busy eating and 

 growing that before they know it they have grown too large to 

 get out, and must remain prisoners for the rest of their lives. 



The teredo, or ship worm, would hardly seem to belong with 

 this group of animals, but it is a true bivalve, having a pair of 

 tiny shells at one end of its wormlike body. It has been a most 

 terrible pest ever since men began to traverse the ocean, for its 

 favorite home is the bottom of a wooden ship. It belongs to a 

 family of borers. Some bore in coral, some in rock, and others 

 in wood. The baby teredo, when floating about in the water, 

 comes across a vessel or piece of wood, and immediately begins to 

 bore into it with the edges of a pair of pallets which it has for 

 the purpose. As it proceeds, a calcareous lining is formed to the 

 burrow, which increases in size as the teredo grows. It never 

 leaves its hole again during life. 



One very curious fact connected with the teredo is that the 

 burrow of one never runs into nor crosses the burrow of another, 

 even though the wood between is no thicker than a sheet of 

 paper. These little fellows work very rapidly, as the following 

 item from Quatrefages will show : A ship was sunk near St. 

 Sebastian, Spain, and in four months, when it was raised, all the 



timbers and planks 

 were so riddled with 

 teredo burrows that 

 they were entirely 

 worthless. 



The most brilliant 

 and withal attractive 

 shells in my collec- 

 tion are from the 

 West Indies. I call 

 them sunset shells, 

 because they look as the sky often does on a beautiful summer 

 evening. They are somewhat like clam shells in shape, but nar- 

 rower and flatter, and most delicately finished. Some are flushed 

 with delicate pink, with rays of pale yellow, others are violet and 

 white, still others green. All the colors of the rainbow are here 

 blended and harmonized with the matchless perfection with which 

 the Great Artist works. 



The univalves are more highly developed than the bivalves. 

 They are called Gasteropods, which means stomach-footed, be- 



fli- 



/''' 



Sunset Shell. 



