Complex sentence: The discovery of these remains prompts Browne to deliver, first, a careful description of the antiquties found, and then moves on to a careful survey of most of the burial and funerary customs, ancient and present, of which Browne's era was aware.
Split into simpler sentences: The discovery of these remains prompts Browne to deliver, first, a careful description of the antiquties found. Browne then gives a careful survey of most of the burial and funerary customs, ancient and current, of which his era was aware.