In a manner relating to or according to the principles and methods of craniology; from the perspective of skull study.
From craniological + '-ly' (manner/way). This adverbial form allows statements about skull characteristics to be qualified 'craniologically' rather than just 'scientifically.'
When a Victorian anthropologist says something is true 'craniologically,' they're appealing to skull measurements as authority—a reminder that fancy adverbs don't make pseudoscience legitimate, they just make it sound more official.
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