STENO 223 



will make the hand of a man without the man himself, 

 and the argument is just as true of sharks' teeth. Lest 

 the great numbers in which the glossopetrae occur should 

 be thought a difficulty they were carried away from 

 Malta in bushels he points out that every shark's jaw 

 contains sixty teeth in good working order, and these as 

 they wear out are continually replaced by fresh ones ; 

 further, he adds, sharks swim about in schools, so that a 

 great many teeth will generally be found bristling about 

 in the same place at the same time. Since sharks are 

 very voracious creatures, the multitude of glossopetrse 

 implies the existence not only of sharks, but of a whole 

 world of other animals, including those which live on 

 cockles and other shell-fish. That we next find Steno 

 giving serious attention to the study of cockle-shells is 

 only, therefore, what we might expect. He patiently 

 traced the manner of their growth, and ascertained, 

 with a degree of accuracy remarkable for those times, 

 the minute details of their structure. From the living 

 cockle he turned to the fossil shells, and by a careful 

 comparison showed how they agree, feature by feature, 

 both in form and more particularly in structure, with 

 their modern representatives. This structure, Steno 

 insists, is the direct result of the manner in which the 

 shell is produced by the animal, and he concludes that 

 the fossil, like the recent cockle-shell, once contained a 

 living cockle inside it. 



Having thus, by close observation and strict logic, 

 breathed life afresh into these fossil remains, Steno pro- 

 ceeded to provide them with an environment : they were 

 bathed, he says, with an ambient fluid, which was none 

 other than sea-water ; hence it follows that the lands in 

 which such fossils occur were once submerged beneath 

 the sea. This conclusion, he pointed out, is in complete 

 harmony with the nature of the material of which the 



