Quoting here from Oudemans’ book:
In 1845 Dr. Albert C. Koch, “exhibited a large skeleton of a fossil animal, under the name of Hydrarchos Sillimanni in Broadway, New York, purporting to be that of an extinct marine serpent. These remains consisted of a head and vertebral column, measuring in all 114 feet, of a few ribs attached to a portion of the latter, and of parts of supposed paddles.”… I will not trouble my readers with it, but only mention that Prof. Wyman in the same paper proved that, “these remains never belonged to one and the same individual, and that the anatomical characters of the teeth indicate that they are not those of a reptile, but of a warm-blooded mammal.”
Note two features of the image. One: some fine top hats there, about the size of the purported paddles. Two: the chapter title running up the right side of the page.