I believe you have it backwards. I'm no expert yet, but I think it should be:

package Module;

...

package Module::Monkey;
use base 'Module';

...

package Module::Ape;
use base 'Module';

...
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Update, book suggestion:
By the way, I would highly recommend the alpaca book that Merlyn wrote. I've just finished my first cover-to-cover read of it and it has finally pried my feeble mind open and made me understand things that I just couldn't wrap my brain around from reading other things.