. Animal activities; a first book in zooÌlogy. Zoology; Animal behavior. 166 /1NIM/4L Fig. 130.âA Squid, its pen. P, Another important class of moUusks is the Cephalop- oda. The squid belongs to this class, as do the octopus, the argonaut, and the pearly nautilus. Characteristics of MoUusca. The name Mollusca is given on account of the fact that the bodies of these animals, ex- cepting the shell, have no hard parts. In Mollusca the body- is typically bilateral. There is a mantle present which in most cases secretes a shell which is as much a part of the animal as is the mantle its
. Animal activities; a first book in zooÌlogy. Zoology; Animal behavior. 166 /1NIM/4L Fig. 130.âA Squid, its pen. P, Another important class of moUusks is the Cephalop- oda. The squid belongs to this class, as do the octopus, the argonaut, and the pearly nautilus. Characteristics of MoUusca. The name Mollusca is given on account of the fact that the bodies of these animals, ex- cepting the shell, have no hard parts. In Mollusca the body- is typically bilateral. There is a mantle present which in most cases secretes a shell which is as much a part of the animal as is the mantle itself. These shells increase in size as the animal grows, and . so exhibit lines of growth. A fleshy foot is also present. The nervous system consists of three pairs of ganglia connected by nerves. Eyes are present in many forms and in the higher cephalopods they closely re- semble the eyes of Vertebrates. In all but the Pelecypoda the mouth is provided with a lingual ribbon, which is a sort of rasp in the mouth by which in many cases thick shells may be bored entirely through. Questions. How do the sense- organs of moUusks' which forage for food compare with those of sedentary mollusks } What protective devices do you observe among mollusks .â " How can one compel an oyster to produce a pearl .'' Topics for Reports. Tyrian Dyes. Eye-stones. The Octopus and Squid. The Chambered Nautilus. 9f^^f^^ Tv"irvi>|, Fig. 131 Part of a Lingual Rib- bon {magnified).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original French, Nathaniel Stowers, 1854-. New York [etc. etc. ] Longmans, Green and Co
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