PHILADELPHIA — On Saturday, the Penn Museum will host a public commemoration and interfaith burial service for 19 unidentified Black Philadelphians, likely enslaved during their lifetimes, who died in the 1830s and 1840s but were never laid to rest. Their skulls were severed from their bodies and stolen by white supremacist scientist Samuel G. Morton, who added them to his collection of more than 1,300 crania — to be examined by anthropologists for nearly 200 years. But this ceremony won’t put to rest the controversy around Penn’s handling of these remains. Instead, it adds another messy chapt…