Opposite to the Grotto del Cane, and immediately joining to the lake, rises the mountain called Astruni, which, having, as I imagine, been thrown up by an explosion of a much later date, retains the conical shape and every symptom of a Volcano in much greater perfection than that I have been describing. The crater of Astruni is surrounded with a wall, to confine boars and deers (this Volcano having been for many years converted to a royal chace). It may be about six miles or more in circumference: in the plain at the bottom of the crater are two lakes; and in some books there is mention made of a hot spring, which I never have been able to find. There are many huge rocks of lava within the crater of Astruni, and some I have met with also in that of Agnano; the cones of both these supposed Volcanos are composed of _tufa_ and strata of loose pumice, fragments of lava and other burnt matter, exactly resembling the strata of Vesuvius. Bartholomeus Fatius, who wrote of the actions of King Alphonso the First (before the new mountain had been formed near Puzzole), conjectured that Astruni had been a Volcano. These are his words: "Locus Neapoli quatuor millia passuum proximus, quem vulgo Listrones vocant, nos unum e Phlegraeis Campis ab ardore nuncupandum putamus." There is no entrance into the crater of either Astruni or Agnano, except one, evidently made by art, and they both exactly correspond with Strabo's description of Avernus; the same may be said of the Solfaterra and the Monte Gauro, or Barbaro as it is sometimes called, which I shall describe presently.