The "Selenus" style was popular in Central Europe during the Biedermeier period of the early to mid 19th century. In 1616 Augustus, the Duke of Brunswick-Luneburg, published the first German chess book under the pseudonym "Gustavas Selenus." "Gustavas" is an anagram of "Augustus" with one "u" replaced by a "v." "Selenus" comes from "Selene," Greek goddess of the moon, a reference to Luneburg. The name stuck.
This example is in a polished bone, and has a nice shiny patina. The kings and queens have rather attractive (and delicate) floral or petal galleries and the horse knight is full of character and looks you in the eye. The set's being sold with an early 19th century mahogany box, once somebody's treasured tea caddy- now used to house the chessmen.