86 THE HALL OF SHELLS. 



times a foot across, delicately porcelainlike, of 

 a light-buff tint, beautifully veined or striped 

 in a zigzag pattern with chestnut brown. The 

 beauty of the nacreous lining of this shell I 

 have no words to describe. It seems a min- 

 gling of the delicate tints of most delicate 

 flowers and the beauty and brilliancy of rarest 

 gems. 



"The shell is divided into chambers, hence 

 the name 'chambered nautilus.' When very 

 young this is not the case, but as the animal 

 increases in size it leaves its first compartment, 

 which becomes an empty chamber, and moves 

 forward to one still larger ; the rim of the shell 

 continues to grow, and back of the little occu- 

 pant a pearly partition is produced. This is 

 repeated from time to time, the little animal 

 always using the room next to the vestibule ; 

 but through all preserving a connection by 

 means of a silvery membranous tube called a 

 siphuncle. 



" But few species of these animals now re- 

 main and they alone in warm seas, but geology 

 shows that both Argonauta and Nautili were 

 very abundant in earlier periods. 



" The fossil ammonite was a kind of ' old- 

 fashioned cousin ' to the nautilus or paper 

 sailor. These are found in great abundance, 



