Might we not hence infer that there was a time when the continent of Africa did not exist? and might not this argument be much extended? It could be combated by none of those causes which are advanced relative to the distribution of species on land; for, 1. The temperature of the water in southern latitudes is very cold at all seasons of the year. 2. These animals are extremely susceptible of all changes of temperature. 3. They have no means of warming themselves by exercise or motion. 4. The species of food which they subsist on is confined to the latitudes in which they themselves live. 5. They would have to traverse great distances in ungenial climes, and contend against adverse winds, the children of placid seas and genial suns hurried into giant waves and chilling storms. 6. It is not probable that they are swept along in currents, from the circumstance that in the one which flows along the coast to the eastward of the Cape we could find none of them, whilst upon its very edge they were in abundance. Could however their eggs be swept along by a current, and after having been wave-tossed for months or years, be at last borne into waters sufficiently warm to hatch them, and the animals, finding themselves in a genial climate, have increased and multiplied? The numerous little animals of the species which I have always considered to be the Velella of Lamarck went sailing merrily by us today; the least breath of wind made them turn round and round; and this was their mode of progression, the animal moved its little sail which I have before mentioned, and worked its tentaculae so vigorously as to make ripples in the water, in the midst of which it went buoyantly floating along. Caught another fish (Stenopteryx Illustration 5) of the same species as that found on the 15th of July. The accompanying figure is drawn from minute measurements. The length of this specimen was 2.5 inches, its thickness through the thickest part 0.38. What I had before imagined to be either a spine or fin turned out to be a pectoral fin. It thus has two pectoral, one dorsal, and one ventral fin, properly speaking; but the greater part of the body is surrounded by some cartilaginous substance which it probably uses as a fin; under the line b c there is a curved portion of this matter, and above and attached to the fish is a line of round white silvery scales, about ten in number.