I ON THE METHOD OF ZADIQ 21 



can say why that sort of head and that sort of tail 

 go together ; what physiological connection there 

 is between the two. So, in the case of the 

 Montmartre fossil, Cuvier, finding a thorough 

 opossum's head, concluded that the pelvis also 

 would be like an opossum's. But, most assuredly, 

 the most advanced physiologist of the present day 

 could throw no light on the question why these 

 are associated, nor could pretend to affirm that the 

 existence of the one is necessarily connected with 

 that of the other. In fact, had it so happened 

 that the pelvis of the fossil had been originally 

 exposed, while the head lay hidden, the presence 

 of the " marsupial bones/' though very like 

 an opossum's, would by no means have war- 

 ranted the prediction that the skull would turn 

 out to be that of the opossum. It might 

 just as well have been like that of some other 

 marsupial ; or even like that of the totally dif- 

 ferent group of Monotremes, of which the only 

 living representatives are the Echidna and the 

 Ornithorhynekus. 



For all practical purposes, however, the empirical 

 laws of co-ordination of structures, which are 

 embodied in the generalisations of morphology, 

 may be confidently trusted, if employed with due 

 caution, to lead to a just interpretation of fossil 

 remains ; or, in other words, we may look for the 

 verification of the retrospective prophecies which 

 are based upon them. 



