that of the solid land fluctuates up and down through thousands
of feet in a secular ground swell, it may well have appeared far
less hazardous to conceive that fossils are sports of nature
than to accept the necessary alternative, that all the inland
regions and highlands, in the rocks of which marine shells had
been found, had once been covered by the ocean. It is not so
surprising, therefore, as it may at first seem, that although
such men as Leonardo da Vinci and Bernard Palissy took just
views of the nature of fossils, the opinion of the majority of
their contemporaries set strongly the other way; nor even that
error maintained itself long after the scientific grounds of the
true interpretation of fossils had been stated, in a manner that
left nothing to be desired, in the latter half of the
seventeenth century. The person who rendered this good service
to palaeontology was Nicolas Steno, professor of anatomy in
Florence, though a Dane by birth. Collectors of fossils at that
day were familiar with certain bodies termed "glossopetrae," and
speculation was rife as to their nature. In the first half of
the seventeenth century, Fabio Colonna had tried to convince his
colleagues of the famous Accademia dei Lincei that the
glossopetrae were merely fossil sharks' teeth, but his arguments
made no impression. Fifty years later, Steno re-opened the
question, and, by dissecting the head of a shark and pointing
out the very exact correspondence of its teeth with the
glossopetrae, left no rational doubt as to the origin of the
latter. Thus far, the work of Steno went little further than
that of Colonna, but it fortunately occurred to him to think out
the whole subject of the interpretation of fossils, and the
result of his meditations was the publication, in 1669, of a
little treatise with the very quaint title of "De Solido intra