78 THE GENESIS OF SPECIES [Chap. 



has elsewhere^ pointed out, tliore is a certain similarity 

 of tlie upper cutting teeth, or incisors. 



Now these correspondences are the more striking when 

 we bear in mind that a similar dentition is often put to 

 very different uses. The food of different kinds of a])OS is 

 very different, yet how uniform is their dental structure ! 

 Afjain, who, lookin*:,^ at the teeth of different kinds of hears, 

 would ever suspect that one kind was frugivorous, and 

 another a devourer exclusively of animal food ? 



The suggestion made hy Professor Huxley was therefoie 

 one which had nmch to recommend it to Darwinians, 

 though it lias not met with any notahle acceptance, and 

 thou'di he seems himself to have returned to the older 

 notion, — namely, that the pouched-l)easts, or marsupials, 

 are a special ancient offshoot from the great mammalian 

 class. 



But whichever view may be the correct one, we have in 

 either case a number of forms similarly modified in har- 

 mony with surrounding conditions, and eloquently ])ro- 

 claiming some natural plastic power, other than mere 

 fortuitous variation with survival of the fittest. If, how- 

 ever, the reader thinks that teeth are parts peculiarly 

 qualiiied for rapid variation (in which view the author 

 cannot concur), he is requested to suspend his judgment 

 till he has considered the question of the independent 

 evolution of the hiyhvst oryans of sense. If this seems to 

 establish the existence of some other law than that of 

 " Natural Selection," then the operation of that other law 

 niay surely be also traced in the harmonious co-ordinations 

 of dental form. 



The other difficulty, kindly suggested to me by the 



1 ♦'Journal of Anatomy and Physiolog>-" (18GS), vol. ii. p. 139. 



