T6 FIRST LESSONS IN ZOOLOGY. 



the mouth is surrounded with ten arms, provided with 

 suckers, while the mouth is furnished with a pair of jaws 

 somewhat like a parrot's bill. The squids are very active, 

 and can dart rapidly backward by ejecting the water from 

 their siphon or funnel. They have large, well-developed 

 eyes, and the brain is large, and protected by an imperfect 

 gristly brain-box. The Octopus has eight arms. To this 



a 



FIG. 80. The whelk. Its tentacles and proboscis extended; , egg-capsules; 

 b, embryo shell. (Natural size.) 



class, called Cephalopoda, also belong the chambered Nau- 

 tilus, and the paper Nautilus. 



Since their bodies are so soft, all univalve and bivalve 

 shell-fish, and certain other animals allied to them, to- 

 gether with the cuttles, etc., are called "molluscs," from 

 the Latin mollis, meaning soft. Molluscs, then, are soft- 

 bodied animals, with a foot or creeping disk, and usually 

 protected by a shell. 



CLASSES OP MOLLTJSCA. 



1. Shell bivalved Lamellibranchiata. Oyster, clam ; eta 



2. Shell univalve CcpMlophora. Snails. 



3. Shell when present coiled; 



8-10 .arras Cephalopoda. Cuttle-fish. 



