Professor Owen would place the sea‐serpent among the mammalia, but _Phoca proboscidea_ is the only seal which will bear comparison with the _Dædalus_ animal in dimensions, it reaching from twenty to thirty feet. The officers declare, however, that at least sixty feet of their animal was visible at the surface. Again, the fore paws of the seal are placed at about one‐third of the total length from the muzzle, and yet no appearance of fins was seen. To continue, the great _Phoca proboscidea_ has no mane, the only seals possessing what may be dignified with the title being the two kinds of sea lions—the _Otaria jubata_ and _Platyrhynchus leoninus_—which are far too small to come into the count. It is quite possible that the great unknown is a reptile, and his marine habits present no difficulty. In the Indian and Pacific Oceans there are numerous specimens of true snakes (_Hydrophidæ_), which are exclusively inhabitants of the sea. None of these, however, are known to exceed a few feet in length, and none of them, so far as is known, have found their way into the Atlantic. The most probable solution of the riddle is the hypothesis of Mr. Morriss Stirling and Professor Agassiz, that the so‐called sea‐serpent will find its closest affinities with those extraordinary animals the _Enaliosauria_, or marine lizards, whose fossil skeletons are found so abundantly through the Oolite and the Lias. If the Plesiosaur could be seen alive you would find nearly its total length on the face of the water propelled at a rapid rate, without any undulation, by an apparatus altogether invisible—the powerful paddles beneath—while the entire serpentine neck would probably be projected obliquely, carrying the reptilian head, with an eye of moderate aperture, and a mouth whose gape did not extend behind the eye. Add to this a body of leathery skin like that of the whale, give the creature a length of some sixty feet or more, and you would have before you almost the very counterpart of the apparition that wrought such amazement on board the _Dædalus_. In evidence of the existence of such an animal, Captain the Hon. George Hope states that when in H.M.S. _Fly_, in the Gulf of California, the sea being perfectly smooth and clear, he saw at the bottom a large marine animal with the head and general figure of an alligator, except that the neck was much longer, and that, instead of legs, the animal had four large flappers, something like those of turtles.