The Marin Humane Society said the large group was dumped in cardboard boxes outside the shelter in the middle of the night.
Surveillance footage shows a vehicle pulling up to the shelter, and three people offloading the boxes of cats with a note asking the shelter to find them homes.
"No one will be held liable, or be in trouble for abandoning the cats, but we're hopeful the responsible party will get in touch with us to provide the needed information," HMS said in a statement.
To help alleviate overcrowding at the shelter, they are waiving adoption fees for all adult cats until the end of September.
More than 130 tuxedo cats have been abandoned at the shelter over the last four years, and none appear to have been spayed or neutered.
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