vessel which the serpent brake, hope to appease the anger of the
Deity by any outward acts of religious, or rather superstitious,
ceremony, such as was that, in our poet's time, performed by a
murderer at Florence, who imagined himself secure from vengeance,
if he ate a sop of bread in wine, upon the grave of the person
murdered, within the space of nine days." 

v.  38.  That eagle.] He prognosticates that the Emperor of
Germany will not always continue to submit to the usurpations of
the Pope, and foretells the coming of Henry VII Duke of
Luxembourg signified by the numerical figures DVX; or, as
Lombardi supposes, of Can Grande della Scala, appointed the
leader of the Ghibelline forces.  It is unnecessary to point out
the imitation of the Apocalypse in the manner of this prophecy. 

v.  50.  The Naiads.] Dante, it is observed, has been led into a
mistake by a corruption in the text of Ovid's Metam.  I.  vii.
75, where he found-
Carmina Naiades non intellecta priorum;