47 6 THE POPULAR SCIENCE MONTHLY. 



not all, of the opossums are provided. As a matter of fact, they have 

 nothing to do with the support of the pouch, and they exist as much 

 in those opossums which have no pouches as in those which possess 

 them. In truth, no one knows what the use of these bones may be> 

 nor has any valid theory of their physiological import yet been sug- 

 gested. And, if we have no knowledge of the physiological impor- 

 tance of the bones themselves, it is obviously absurd to pretend that 

 we are able to give physiological reasons why the presence of these 

 bones is associated with certain peculiarities of the teeth and of the 

 jaws. If any one knows why four molar teeth and an inflected angle 

 of the jaw are almost always found along with marsupial bones, he 

 has not yet communicated that knowledge to the world. 



If, however, Zadig was right in concluding from the likeness of 

 the hoof -prints which he observed to a horse's that the creature which 

 made them had a tail like that of a horse, Cuvier, seeing that the teeth 

 and jaw of his fossil were just like those of an opossum, had the same 

 right to conclude that the pelvis would also be like an opossum's ; and 

 so strong was his conviction that this retrospective prophecy about an 

 animal which he had never seen before, and which had been dead and 

 buried for millions of years, would be verified, that he went to work 

 upon the slab which contained the pelvis in confident expectation of 

 finding and laying bare the " marsupial bones," to the satisfaction of 

 some persons whom he had invited to witness their disinterment. As 

 he says : " Cette operation se fit en presence de quelques personnes a 

 qui j'en avais annonce d'avance le resultat, dans l'intention de leur 

 prouver par le fait la justice de nos theories zoologiques ; puisque le 

 vrai cachet d'une theorie est sans contredit la faculte qu'elle donne de 

 prevoir les phenomenes." 



In the " Ossemens fossiles," Cuvier leaves his paper just as it first 

 appeared in the " Annales du Museum," as " a curious monument of 

 the force of zoological laws and of the use which may be made of 

 them." 



Zoological laws truly, but not physiological laws. If one sees a 

 live dog's head, it is extremely probable that a dog's tail is not far 

 off, though nobody 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 opos- 

 sum's. But, most assuredly, the most advanced physiologist of the 

 present day could throw no light on the question why these are asso- 

 ciated, nor could pretend to affirm that the existence of the one is neces- 

 sarily 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," however like they 

 might have been to an opossum's, would by no means have warranted 

 the prediction that the skull would turn out to be that of the opossum. 



