The ship Dana made another expedition after the trip to the Sargasso Sea. It was an expedition around the world, made in 1928-1930. The collection of specimens made during this expedition is now at the Marinebiologisk Laboratorium in Charlottenlund, Denmark, under the care of Dr. Åge Vedel Tåning, who accompanied Dr. Schmidt on his later trips. And in this collection is a Leptocephalus taken, according to a letter from Dr. Tåning, on January 31, 1930, from a depth of about 1000 feet west of of the Agulhas Bank, off the southernmost point of Africa. Dr. Tåning supplied me with the precise location: 35 degrees, 42 minutes, south, and 18 degrees, 37 minutes, east. This Leptocephalus is 184 centimeters long -- 6 feet and 1/2 inch.
Nobody knows the adult form.
It may be a kind of salt-water eel which grows to its full size as a Leptocephalus and changes into an adult form which is not appreciably larger. If it grows in the same proportion as the ordinary eel, the result would be a monster between 60 and 70 feet long. I don't suggest that this is the "great sea serpent." But, like everybody else who knows about it, I wonder what it would have grown into.
I've not had time to check up on whether anything new was learned about this specimen (the book was originally published in 1959), but one can't help but wonder if mommy lives in Loch Ness? ;-)