308 MANUAL OF ZOOLOGY SECT, xi 



The sexes are distinct. The ova are always large, con- 

 taining a large quantity of yolk. No metamorphosis, such 

 as is general in other groups of Mollusca, is known to occur 

 in any Cephalopod. 



The Cephalopoda are all marine, and range from tidal 

 limits to a considerable depth. A large number are pelagic. 

 They are, nearly without exception, carnivorous. In length 

 they range from an inch or two to as much as fifty feet the 

 gigantic members of the group, such as Architeuthis^ being 

 by a long way the largest of invertebrate animals. Like the 

 other classes of Mollusca they are most abundant in tropical 

 and warm temperate seas. 



