(from the article `snake`) ...surfaces that lie above and below; and finally the zygosphenes and zygantra, found almost exclusively in snakes, the zygosphene being a projecting ... Found on http://www.britannica.com/eb/a-z/z/13
Zy·gan'trum noun ; plural Zygantra . [ Greek zygo`n a yoke + ... a cave, hole.] (Anat.) See under Zygosphene . Found on http://www.encyclo.co.uk/webster/Z/7