Possible Clues:

• Crawls as a snake would
• Moves like an anaconda
• Makes like a snake
• Slides unobtrusively, perhaps slyly
• Leaves no footprints, in a way
• Moves sinuously
• 'Slides unobtrusively, perhaps slyly (8)'
• Makes moccasin tracks
• The woman getting into narrow openings slides
• Moves like a lizard