Narceus americanus produces four different burrow architectures, each with multiple possible modifications including the addition of chambers, branches, spirals, and surface openings.
Open burrows are used as temporary shelters to permanent dwellings. Burrows are generally vertical (75-90 degrees) in orientation, but individual elements may also be horizontal (0-5 degrees) to oblique (15-50 degrees). Shafts and tunnels are circular in cross section (W/H ratio ~1.0) with relatively a consistent circumference along their length. Tunnels are straight to sinuous. Branching is uncommon but does occur in some vertical burrows. Chambers are two to three times larger than the connecting shaft or tunnel. Burrows were kept open while occupied and not backfilled.
Additional resources are available within the downloadable PDF and Excel files linked at the bottom of the page.
Additional resources
North American Millipede Burrow Catalog (PDF)
North American Millipede Burrow Info Packet (PDF)
North American Millipede Burrow Data Spreadsheet (Microsoft Excel – Auto Download)