STRTJCTrRE AND rKYSIOLOGT OF THE MOLLUSCA. 



1, 



Lastly, the moUusca exhibit the same instinctive care "svith 

 insects and the higher animals in placing their eggs in situations 

 ^vhere they will be safe from injury, or open to the influences 

 of air and heat, or surrounded by the food which the young 

 will require. The tropical huJimi cement leaves together to 

 protect and conceal their large bird-like eggs ; the slugs bury 

 theirs in the ground ; the oceanic-snail attaches them to a 

 floating raft ; and the argonaut carries them in her frail boat. 



Fig. 9. lanthina with its raft. 



The horny capsules of the whelk arc clustered in groups, with 

 spaces pervading the interior for the free passage of sea water ; 

 and the nidamental ribbon of the doris and eolis is attached to a 

 rock or some solid surface from which it will not be detached by 

 the waves. The river-mussel and cydas carry their i)arental 

 care still further, and nurse their young in their own mantle, 

 or in a special marsiipium, designed like that of the opossum, 

 to protect them until they are strong enough to shift for 

 themselves. 



If any one imbued with the spirit of Paley or Chateaubriand, 

 should study these phenomena, he might discover more than 

 the " barren facts " which alone appear without significance to 

 the unspiritual eye ; he would see at every step fresh proofs of 

 the wisdom and goodness of God, who thus manifests His great- 

 ness by displaying the same care for the maintenance of His 

 feeblest creatures as for the well-being of man and the stability 

 of the world. 



Strtjctuee akd Physiology of the Mollusca. 



Molluscous animals possess a distinct nervous system, instru- 

 ments appropriated to the five senses, and muscles by which 

 they execute a variety of movements. They have organs, by 

 which food is procured and digested; a heart, with arteries 

 and veins, through which their colourless fluids circulate ; a 



