Dr. Myron Gordon did extensive experimentation on swords in the mid 20th century in fields of genetics and cancer. This is a photo accompanying an article he wrote and what's significant about it is, it's widely believed that only X. montezumae had a long "sword" but this photo of X. helleri clearly shows that is not actually true. Long sword X. helleri do in fact exist. It's a pity the exact location in Mexico was not given.