Why is a smooth shell suited to a clam and a rough shell suited to an oyster? Why are the turns of a snail's shell so small near the center?
Why does the mussel have no use for head, eyes, or projecting feelers? In what position of the valves of a mussel is the hinge ligament in a stretched condition? How does the shape of the mussel's gills insure that the water current and blood current are brought in close contact?
The three classes of mollusks are: the pelecypoda (hatchet-footed); gastropoda (stomach-footed); and cephalopoda (head-footed). Give an example of each class.
Comparison of Mollusks
==========+==========+==========+==========
| Mussel | Snail | Squid
+++
Shell | | |
+++
Head | | |
+++
Body | | |
+++
Foot | | |
+++
Gills | | |
+++
Eyes | | |
====+==========+==========+====
Comparative Review.—(To occupy an entire page in notebook.)
============+===========+========+========+=========+=========
|Grasshopper| Spider |Crayfish|Centipede| Mussel
+-+++-+-
| | | | |
Bilateral | | | | |
or radiate | | | | |
+-+++-+-
Appendages | | | | |
for | | | | |
locomotion | | | | |
+-+++-+-
Names of | | | | |
divisions | | | | |
of body | | | | |
+-+++-+-
Organs and | | | | |
method of | | | | |
breathing | | | | |
+-+++-+-
| | | | |
Locomotion | | | | |
| | | | |
