312 PALAEONTOLOGY 



certain established laws of correlated structures, an extinct 

 animal may be re-constructed from a single tooth or from a 

 fragment of bone 1 Is the Cuvierian basis, or what has been 

 so regarded, of palaeontology unsound ? Not necessarily from 

 aught that has been said or written on the subject of the 

 Stereognathus. We do not know the comparative anatomy of 

 the family of quadrupeds to which the Stereognathus belonged. 

 What we do know of its teeth suggests that that family may 

 have had modifications of the skeleton so far different from 

 those of any, the modifications of winch are known, as to have 

 constituted a type of, perhaps, a marsupial family ; but a type 

 as well marked, and as distinct, as the type of skeleton which 

 Cuvier inductively studied in the feline Carnivora (fig. 128), 

 and in the ruminant Herbivora (fig. 129), and by which pre- 

 liminary study he was enabled to enunciate that beautiful law 

 of the " correlation of forms and structures" to which allusion 

 has been already made, and which will be illustrated by exam- 

 ples, and its mode of application pointed out, in another part 

 of the present work. 



In certain instances of constant coincidences of structure, 

 as demonstrated by comparative anatomy, the sufficient — i. e. 

 recognizable, intelligible, or physiological — cause of them is not 

 yet known. But, as Cuvier in reference to such instances truly 

 remarks, " Since these relations are constant, there certainly 

 must be a sufficient cause for them." * In certain other cases 

 Cuvier believed that he could assign that " sufficient cause," 

 and he selects, as such, the correlated structures in a feline 

 Carnivore, and in a hoofed Herbivore. The physiological know- 

 ledge displayed by him in his explanation of the condition of 

 those correlations is most exact : its application in the restora- 

 tion of the Anoplotherium and Palceotheriv/m most exemplary. 



In the ratio of the knowledge of the reason of the coinci- 

 dences of animal structures-- in oilier words, as those coinci- 



* Discours sur les Revolutions do la Surface du Globe, ito, 1826, p. 50. 



