Again, though it be not impossible, yet it is surely very rare: as we are induced to believe from some enquiry of our own, from the trial of many who have been deceived, and the frustrated search of _Porta_, who upon the explorement of many, could scarce find one. Nor is it only of rarity, but may be doubted whether it be of existencie, or really any such stone in the head of a Toad at all. For although _Lapidaries_ and questuary enquirers affirm it, yet the Writers of Minerals and natural speculators, are of another belief: conceiving the stones which bear this name, to be a Mineral concretion; not to be found in animals, but in fields. And therefore _Bœtius_ refers it to _Asteria_ or some kind of _Lapis stellaris_, and plainly concludeth, _reperiuntur in agris, quos tamen alii in annosis ac qui diu in Arundinetis inter rubos sentesque delituerunt bufonis capitibus generari pertinaciter affirmant_. Lastly, If any such thing there be, yet must it not, for ought I see, be taken as we receive it, for a loose and moveable stone, but rather a concretion or induration of the crany it self; for being of an earthy temper, living in the earth, and as some say feeding thereon, such indurations may sometimes happen. Thus when _Brassavolus_ after a long search had discovered one, he affirms it was rather the forehead bone petrified, then a stone within the crany; and of this belief was _Gesner_. Which is also much confirmed from what is delivered in _Aldrovandus_, upon experiment of very many Toads, whose cranies or sculs in time grew hard, and almost of a stony substance. All which considered, we must with circumspection receive those stones which commonly bear this name, much less believe the traditions, that in envy to mankind they are cast out, or swallowed down by the Toad; which cannot consist with _Anatomy_, and with the rest, enforced this censure from _Bœtius_, _Ab eo tempore pro nugis habui quod de Bufonio lapide, ejusque origine traditur._ What therefore best reconcileth these divided determinations, may be a middle opinion; that of these stones some may be mineral, and to be found in the earth; some animal, to be met with in Toads, at least by the induration of their cranies. The first are many and manifold, to be found in _Germany_ and other parts; the last are fewer in number, and in substance not unlike the stones in Crabs heads. This is agreeable unto the determination of _Aldrovandus_[SN: De Mineral. lib. 4. Musæi Calceolariani, Sect. 3.], and is also the judgment of learned _Spigelius_ in his Epistle unto _Pignorius_.