PREFACE. xxix 



CuviER, ' whether I shovild have ever divined, if observation had 

 not taught it me, that the ruminant hoofed beasts slioukl all have 

 the cloven-foot, and be the only beasts with horns on the frontal 

 bone.' ' I may add that we know as little why horns should be in 

 one or two pairs in those ungulates only which have hoofs in one 

 or two pairs ; whilst in the horned ungidates with three hoofs 

 there should be either one horn, or two odd horns placed one be- 

 hind the other, in the middle line of the skull ; or why the ungu- 

 lates with one or three hoofs on the hind foot should have three 

 trochanters on the femur, whilst those with two or four hoofs on 

 the hind foot should have only two trochanters.^ 



' However,' continues Ccjvier, ' since these relations are con- 

 stant, they must have a sufficing cause ; but as we are ignorant 

 of it, we must supply the want of the theory by means of observa- 

 tion. This wll serve to establish empirical laws if adequately 

 pursued, as sure in their application as rational ones.' ^ 'That 

 there are secret reasons for all these relations oljservation may 

 convince us, independently of general philosophy.' ' The con- 

 stancy between such a form of such organ and such another fomr 

 of another organ is not merely specific, but one of class with a 

 corresponding gradation in the development of the two organs.' ^ 



' For examjjle, the dentary system of non-ruminant imgulates 

 is o-enerally more perfect than that of the bisulcates ; inasmuch 

 as the former have almost always both incisors and canines in the 

 upper as Avell as the lower jaw ; the structure of their feet is in 

 c-eneral more complex, inasmuch as they have more digits or hoofs 

 less completely enveloping the phalanges, or more bones distinct 



1 Op. cit. 50. 2 Quarterlj' Journal of the Geological Societ)', p. 138. 1847- 



' ' Puisqiie ces rapports sont constants, il faut bien qu'ils aient une cause suiEsanto, 

 mais corame nous ne la connaissons pas, nous devous suppleer au defaut de la theorie 

 par le moj-en de robservatioii.' — Op. cit. p. 50. 



■' ' En effet, quand on forme un tableau de ces rapports, on y remarqne non seulement 

 une consistance specifique, si Ton peut s'exprimer ainsi, entre telle forme de tel organe 

 et telle autre forme d'uil organ different ; mais Ton apercjoit aussi une Constance 

 classique et une gradation correspondante dans le dereloppement de ces deux organes, 

 qui montrent, presque aussi bien qu'un raisonnement effectif, leur influence mutuelle.' — 

 Op. cit. p. 51. 



