Yes, Bernard, Il Carnivale di Venezia was indeed composed by Briccialdi, but the original tune, (often used for the song "Mein Hutte hat drei Ecke) was in itself taken from an old Neapolitan canzonetta, which began "O cara mamma mia...". which is at least 200 years old. Nobody knows who originally wrote that, or exactly when. Paganini composed the variations on it (he was quite fond of 'variations'!) in the early 19th century. So this little tune has quite a long and intriguingly complex history.