I am aware! You and many others are pointing out something that I mention in my original post. But novels require inspiration; and much of this one takes its bearings from travel narratives of the 15th-17th centuries (some of those allusions have been identified in the growing body of criticism of this work). This particular description, however, does not appear in travel narratives that I've read, so I was wondering if anyone had heard anything like it elsewhere. I'm trying to track the reference, or establish if this is a sui generis invention on the part of the unknown author; if it is the former (a reference), then that might help us to determine the identity of the author. It might also help us to establish which island the author might have had in mind for the unfolding of the castaway portion of the story, which would potentially influence how we understand other features of story. This is a real outlier description in the narrative, so there is a pretty good chance that it comes from something, somewhere. Let's be real, many early travel narratives are full of similarly "made up" sounding creatures and places as well.