II PROGRESS OF PALEONTOLOGY 29 



as the expression of a process of development in 

 the opposite direction from the mineral to the 

 organic. Moreover, in an age when it would have 

 seemed the most absurd of paradoxes to suggest 

 that the general level of the sea is constant, while 

 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 surpris- 

 ing, 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 con- 

 temporaries set strongly the other way ; nor even 

 that error maintained itsjelf 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 paleontology was Nicolas Steno, pro- 

 fessor 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 



