The polka evolved during the same period into different styles and tempi. In principle, the polka written in the 19th century has a four-theme structure; themes 1A and 1B as well as a 'Trio' section of a further two themes. The 'Trio' usually has an 'Intrada' to form a break between the two sections. The feminine and graceful 'French polka' (polka française) is slower in tempo and is more measured in its gaiety. Johann Strauss II's , Op. 114, "Demolirer-Polka, Op. 269, the "Im Krapfenwald'l", Op. 336, and the "Bitte schön!" polka, Op. 372, are examples of this type of polka. The polka-mazurka is also another variation of the polka, being in the tempo of a mazurka but danced in a similar manner as the polka. The final category of the polka form around that time is the "Polka schnell", which is a fast polka or "galop". Eduard Strauss is better known for this last category, as he penned the "Bahn Frei" polka, Op. 45, and other examples. Earlier, Johann Strauss I and Josef Lanner wrote polkas designated as a "galop" (quick tempo) or as a regular polka that may not fall into any of the categories above.