The Corpus Callosum. You can go to Neuroscience for Kids to find
answers like that.
*Actually, the Corpus Callosum is the structure, but the type of
tract is commisural.
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The Audubon Society online has many wonderful resources for bird
guides. Local bookstores and are also likely to have guides of this
nature. Finally your local Department of Wildlife will have many
resources available to gather information.