The archlute is a large bass lute which has extra strings to produce a deep sound for basso continuo parts. Originally developed in about 1600, it's a compromise between a Renaissance tenor lute and the unwieldy theorbo.
A selection of articles about archlute music
CD Spotlight. Handel and the Roman Baroque School - Giuseppe Pennisi listens to Lorenzo Tozzi's Romabarocca Ensemble. '... a precious CD from which to learn little known aspects of baroque music ...'