Octadecagon and 2{9/4} or two enneagrams, {18/6} is reduced to 6{3} or 6 equilateral triangles, and finally {18/9} is reduced to 9{2} as nine digons. Deeper truncations of the regular enneagon and enneagrams can produce isogonal (vertex-transitive) intermediate octadecagram forms with equally spaced vertices and two edge lengths. Other truncations form double coverings: t{9/8}={18/8}=2{9/4}, t{9/4}={18/4}=2{9/2}, t{9/2}={18/2}=2{9}. The regular octadecagon is the Petrie polygon for a number of higher-dimensional polytopes, shown in these skew orthogonal projections from Coxeter planes: Octadecagon An octadecagon (or octakaidecagon) or 18-gon is an eighteen-sided polygon. A "regular octadecagon" has a Schläfli symbol {18} and can be constructed
Many-finned sea serpent Wake of Bernard Heuvelmans" that the evidence points towards an invertebrate rather than a cetacean identity, and has speculated that the con-rit might be a fully aquatic descendent of the giant myriapod "Arthropleura", which became extinct at the beginning of the Permian period. He has also suggested an alternative to Heuvelman's original binomial name for it in the form of "Mariascolpendra aelani" (Woodley, 2007), which translates as 'Aelian's sea centipede'. Many-finned sea serpent The many-finned sea serpent is an unverified species or group of species of marine animals which seem to possess numerous fins along their sides or backs. The