Final answer:
The lines in Canto XVII invoke the connotation of surprise.
Step-by-step explanation:
The lines 'The face was as the face of a just man, Its semblance outwardly was so benign, And of a serpent all the trunk beside' in Canto XVII invoke the connotation of surprise. The juxtaposition of a just and benign face with the body of a serpent creates a sense of unexpectedness and astonishment. This connotation contributes to the overall meaning and mood of the canto.
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