Further, Owen had the opportunity of listening to some of the debates between Cuvier and Geoffrey Saint-Hilaire on the question of how new species may originate; and ‘on returning home,’ he adds, ‘I was guided in all my work with the hope or endeavour to gain inductive ground for conclusions on these great questions.’ Here, then, was the definite educational result which Owen gained from his visit. It had, moreover, another consequence. It made him known to the French naturalists, then in the front rank of science. His scientific acquirements, coupled with his agreeable manners and facility in speaking and writing French, made him a _persona grata_ in Paris. In 1839 he was elected a corresponding member of the Institute, and read more than one paper there in French. We have already mentioned the long line of scientific papers which, from 1830 onwards, were the result of Owen’s indomitable energy. This series was now to be interrupted for a moment by the famous _Memoir on the Pearly Nautilus_, a quarto volume of sixty-eight pages, illustrated by eight plates, drawn by himself. The shell of the nautilus, as most persons know, has always been fairly common; but the animal which was given to the Museum of the College of Surgeons in 1831 was, we believe, the first, or nearly the first, which had ever reached this country, and Owen was most fortunate in having the chance of describing such a rarity. His essay, elaborate and exhaustive as it is, was dashed off in less than a year. It was received with a general chorus of praise. Dr Buckland spoke of it as ‘Mr Owen’s admirable work,’ and they were soon in correspondence on the way in which the nautilus sinks and rises in the water. Milne Edwards translated it into French, and Oken into German. Nor has the contemporary verdict been reversed by that of posterity. Mr Huxley says of the _Memoir_ that it ‘placed its author, at a bound, in the first rank of monographers. There is nothing better in the _Mémoires sur les Mollusques_, I would even venture to say nothing so good, were it not that Owen had Cuvier’s great work for a model; certainly, in the sixty years that have elapsed since the publication of this remarkable monograph it has not been excelled’ (ii. 306). This essay seems to have given Owen a taste for the group to which the nautilus belongs. At the conclusion of the _Memoir_ he proposed a new arrangement of it, now generally accepted, which includes the fossil as well as the recent forms; and, as occasion presented itself, he described other species and genera. The merit of a memoir on the fossil group called ‘belemnites,’ from the Oxford Clay, was the cause assigned for the award to him of the gold medal of the Royal Society in 1846.