These marks consist primarily or entirely of creatures-- mammals, insects, fish, birds, or any other animate organism other than man-- used by unidentified ceramicists.
If you recognize a mark or can offer information on it, please contact the Moderator.
Walter Del Pellegrino has suggested that the MCP (#3) stands for Manifattura Colonelli Piediluco (made by the Colonelli factory in Piedilucco). He quotes from the 1928 Carbone export catalogue:
...[H]igh up in the hills of Umbria ...the factory was rescued from oblivion by Cavaliere Colonelli ... and is under the artistic direction of Sig. Bazzotti.
This assumption sees likely to be correct, but Del Pellegrino would welcome verification.