Again, if any such thing there were, it were not to be obtruded by the name of _Amphisbæna_, or as an Animal of one denomination; for properly that Animal is not one, but multiplicious or many, which hath a duplicity or gemination of principal parts. And this doth _Aristotle_ define, when he affirmeth a monster is to be esteemed one or many, according to its principle, which he conceived the heart, whence he derived the original of Nerves, and thereto ascribed many acts which Physitians assign unto the brain: and therefore if it cannot be called one, which hath a duplicity of hearts in his sense, it cannot receive that appellation with a plurality of heads in ours. And this the practice of Christians hath acknowledged, who have baptized these geminous births, and double connascencies with several names, as conceiving in them a distinction of souls, upon the divided execution of their functions; that is, while one wept, the other laughing; while one was silent, the other speaking; while one awaked, the other sleeping; as is declared by three remarkable examples in _Petrarch_, _Vincentius_ and the _Scottish_ History of _Buchanan_.
It is not denied there have been bicipitous Serpents with the head at each extream, for an example hereof we find in _Aristotle_, and of the like form in _Aldrovandus_ we meet with the Icon of a Lizzard; and of this kind perhaps might that _Amphisbæna_ be, the picture whereof _Cassianus Puteus_ shewed unto the learned _Faber_. Which double formations do often happen unto multiparous generations, more especially that of Serpents; whose productions being numerous, and their Eggs in chains or links together (which sometime conjoin and inoculate into each other) they may unite into various shapes and come out in mixed formations. But these are monstrous productions, beside the intention of Nature, and the statutes of generation, neither begotten of like parents, nor begetting the like again, but irregularly produced, do stand as Anomalies in the general Book of Nature. Which being shifts and forced pieces, rather then genuine and proper effects, they afford us no illation; nor is it reasonable to conclude, from a monstrosity unto a species, or from accidental effects, unto the regular works of Nature.