Merwin is a merman from Xanth. He was first mentioned in Heaven Cent.
Merwin is the husband of Melantha and father of Merci.
Merwin died by discovering the hard way the differences between games of mermen and dragons. He lost the Firewater Opal to Draco.
Novels: Heaven Cent, The Color of Her Panties
Human men and women will not have a species in their entries. Also, if the surname of the character is the character's species, it was dropped.
If the character is a child, it will be in the description. The child will more than likely be an adult by this time in the Xanth series.
Many species are single gender, so their entries will not mention it. The species are Fury, Muse, basilisk, cenmaid, cenmare, cockatrice, dryad, maenad, sand witch, sandman, and woodwife. Harpies and nymphs are usually female, and fauns are usually male; but there have been a few exceptions that are noted.
In some instances, I have made educated guesses on gender, species, and some birth years.