The bugle is a small artificial flared pipe with no fingerholes. In order to reduce its handling length, it is bent into its familiar curled shape. The bugle is an ancient instrument, and probably dates back as far as the beginnings of the bronze era. It can be regarded as an animal horn made from an artificial material. The English word bugle is derived from the Latin "buculus", which means bullock.
Pitch is varied by different shapes of the human lips of musicians, which act as modifiers. The lips vibrate to act as pitch controllers and create sound through the Bernoulli Effect.
Source:
http://en.wikipedia.org/wiki/File:1911_EB_Roman_Bugle.png
http://en.wikipedia.org/wiki/File:Bugle-rhside-large-1-.jpg
http://www.hark.com/clips/yqxnncrbjk-trumpetbuglecallho-ac051701
http://www.soundsnap.com/music_samples_single/brass_woodwinds