316 THE OCEAN WORLD. 



CHAPTEK XL 



ACEPHALOUS MOLLUSCA. 



"Sigillatitn mortales, cunctum perpetui." 



AfULEius. 



THE Mollusca proper were divided by Cuvier into five great classes : 

 I. Lamellibranchiata, or Acephalous Mollusca, often called Conch- 

 ifera. II. Brachiopoda. III. Gasteropoda. IV. Pteropoda. 

 V. Cephalopoda. 



The name Mollusca indicates the characters which most struck the 

 ancients : they are soft in Latin, mollis : their flesh is cold, humid, 

 and viscous. In consequence of their very softness, they are generally 

 furnished with an apparatus of defence or protection, in the shape of 

 a calcareous cuirass, called a shell. According to the species this 

 test is a coat of mail, a buckler, or a tower. The mollusc is thus 

 armed and defended against all attacks from without, nearly after the 

 manner of a knight of the middle ages; only the knight was not 

 quite shut up in his armour, while the mollusc is attached to it by 

 indissoluble organic bonds. "Such a life and such a habitation!" 

 says Michelet. " In no other creature is there the same identity 

 between the inhabitant and the nest. Drawn from its own substance, 

 the edifice is the continuation of its fleshy mantle. It follows its form 

 and tints. The architect has communicated its own substance to the 

 edifice." 



The shell of the Mollusca has been variously appreciated by natural- 

 ists. " We might regard the shell as the bone of the animal which 

 occupies it," says a celebrated French naturalist ; and then gives ex- 

 pression to a very different view. " We may say as a general thesis 



