http://slugsite.us/bow2007/nudwk568.htm
http://www.underwaterkwaj.com/nudi/hawaii/hc35.htm
http://www.seaslugsofhawaii.com/species/Siphopteron-quadrispinosum-a.html
http://www.nudipixel.net/species/siphopteron_quadrispinosum/
http://www.medslugs.de/E/Pac/Siphopteron_quadrispinosum/Selection.htm