Company employees made the find when they ran the plush bears under an x-ray machine during a routine inspection, the Mexico City public prosecutor's office said yesterday.
The human remains "appear to have been recently exhumed," the office said in a statement.
Authorities contacted and arrested the man who was mailing the package, who said he bought the skills at a popular downtown Mexico City market.
The man said the skulls "are in demand abroad by people who practice santeria," an Afro-Caribbean syncretic religion.
The statement did not say where the teddy bears were being mailed to.
