598 



THE CONE-SHELLS AND THE COWRIES. 



continual addition made to its length is probably to be found in the 

 growth of the madrepore in which it is sheltered, and which would 

 soon enclose the Magilus within its stony walls did not the mollusc 

 provide against such a fate by lengthening its shell and taking up its 

 residence in the mouth. 



The most curious point, however, in the economy of the Magilus is 

 that as fast as it adds a new shell in front it fills up the cavity behind 

 with a solid concretion of shelly matter, very hard and of an almost 

 crystalline structure, so as to leave about the same amount of space as 

 in the original shell. The animal is always to be found in the very 

 front of the shelly tube, and closes the aperture with a strong operculum 

 that effectually shields it against all foes. 



We now pass to the Cone-shells, or Conidse, a family so called on 

 account of their form. All the Cones have a similar external outline : 

 the aperture is long and narrow, the head of the living animal is more 

 or less lengthened, the foot is splay and abruptly cut off in front, the 

 tentacles are rather widely separate, and the eyes are placed upon these 

 organs. 



The Textile Cone-shell comes from the Mauritius. This hand- 

 Bome species is about four or five inches in length and its markings are 

 curiously disposed, so that it is impossible to say 

 which is the ground-color. The dark, narrow, an- 

 gular lines are dark brown, accompanied by white, 

 and variegated by dashes of yellow umber. The 

 bold triangular spots are pure white, and the inside 

 of the shell is of the same color. 



The Admiral Cone, in common with the other 

 members of tlie genus, haunts the fissures and holes 

 in rocks and the warmer pools in coral reefs. They 

 all take a moderate range of depth, varying from 

 one to forty fathoms. 



We now come to the family of the Cowries, or 

 Cyprseidse. All the Cowries are lovers of the shal- 

 low waters near shore, and are carnivorous in their 

 habits, feeding mostly upon the numerous zoophytes 

 that inhabit the same coasts. These shells change 

 their forms in a truly remarkable manner. When 



(cl!rL':;^//?sr'' ^''"''^ ^^^ '^^^^ ^' ""^^^ ^'^^ *^^* ^^ ^ ^^^"*^' ^^'''"^ 



'a prominent spire and a rather wide-spreading lip, 

 but in process of time the lobes of the mantle expand over it on either 

 side, and by degrees deposit so thick a layer of smooth, shining sub- 

 stance that the spire is entirely hidden. The pale streak which gen- 

 erally exists along the back of the Cowries indicates the line where the 

 edges of the mantle nearly meet. 



