Scarce swallowtail Scarce swallowtail The scarce swallowtail ("Iphiclides podalirius") is a butterfly belonging to the family Papilionidae. It is also called the sail swallowtail or pear-tree swallowtail. Subspecies include: "Iphiclides podalirius feisthamelii" is sometimes treated as a valid species, "Iphiclides feisthamelii". Despite the name "scarce swallowtail", this species is quite common. The scarcity of United Kingdom migrants is responsible for the English vernacular name. This species is widespread in the East Palearctic ecozone and in most of Europe with the exception of the northern parts. Its range extends northwards to Lower Lusatia and central Poland and eastwards across Asia Minor and Transcaucasia
Syntonic comma Syntonic comma In music theory, the syntonic comma, also known as the chromatic diesis, the comma of Didymus, the Ptolemaic comma, or the diatonic comma is a small comma type interval between two musical notes, equal to the frequency ratio 81:80 (= 1.0125) (around 21.51 cents). Two notes that differ by this interval would sound different from each other even to untrained ears, but would be close enough that they would be more likely interpreted as out-of-tune versions of the same note than as different notes. The comma is referred to as a "comma of Didymus" because it is the