[Footnote:  The passages, here given from the MS. Leic., have hitherto remained unknown.  Some preliminary notes on the subject are to be found in MS. F 8oa and 8ob; but as compared with the fuller treatment here given, they are, it seems to me, of secondary interest.  They contain nothing that is not repeated here more clearly and fully.  LIBRI, Histoire des Sciences mathematiques III, pages 218—­221, has printed the text of F 80a and 80b, therefore it seemed desirable to give my reasons for not inserting it in this work.]

That marine shells could not go up the mountains.

987.

OF THE DELUGE AND OF MARINE SHELLS.

If you were to say that the shells which are to be seen within the confines of Italy now, in our days, far from the sea and at such heights, had been brought there by the deluge which left them there, I should answer that if you believe that this deluge rose 7 cubits above the highest mountains—­ as he who measured it has written—­these shells, which always live near the sea-shore, should have been left on the mountains; and not such a little way from the foot of the mountains; nor all at one level, nor in layers upon layers.  And if you were to say that these shells are desirous of remaining near to the margin of the sea, and that, as it rose in height, the shells quitted their first home, and followed the increase of the waters up to their highest level; to this I answer, that the cockle is an animal of not more rapid movement than the snail is out of water, or even somewhat slower; because it does not swim, on the contrary it makes a furrow in the sand by means of its sides, and in this furrow it will travel each day from 3 to 4 braccia; therefore this creature, with so slow a motion, could not have travelled from the Adriatic sea as far as Monferrato in Lombardy [Footnote:  Monferrato di Lombardia.  The range of hills of Monferrato is in Piedmont, and Casale di Monferrato belonged, in Leonardo’s time, to the Marchese di Mantova.], which is 250 miles distance, in 40 days; which he has said who took account of the time.  And if you say that the waves carried them there, by their gravity they could not move, excepting at the bottom.  And if you will not grant me this, confess at least that they would have to stay at the summits of the highest mountains, in the lakes which are enclosed among the mountains, like the lakes of Lario, or of Como and il Maggiore [Footnote:  Lago di Lario. Lacus Larius was the name given by the Romans to the lake of Como.  It is evident that it is here a slip of the pen since the the words in the MS. are:  "Come Lago di Lario o’l Magare e di Como," In the MS. after line 16 we come upon a digression treating of the weight of water; this has here been omitted.  It is 11 lines long.] and of Fiesole, and of Perugia, and others.