The Bostillon is from pure breed parents, the Boston Terrier and the Papillon, also known as the Continental Toy Spaniel.
The Boston Terrier, a sturdy but lithe, dapper little dog, originated from its namesake city and is one of the more popular pet and companion dogs in the US. Bred only in the late 1800's, it is a relatively young breed, and some breeds thought to have contributed to its lineage include bull and terrier types, the modern English bulldog, and the French bulldog. Despite the name, the Boston Terrier differs from terriers in general when it comes to its brachycepahlice appearance and gentler, more relaxed disposition.
The Papillon is one of two breed types from the same litter. A dainty spaniel valued as a lap dog and companion, the Papillon, so-called because of the butterfly-shaped fringe of fur around its ears, shares the line with a drop-ear type, called the Phalene. The Papillon, one of the oldest spaniel breeds, originated in France and has been popular throughout the centuries in various European countries as well, associated at times with various royal houses.