in the Reconstruction of extinct Vertebrate Forms. 489 



works; 2nd, empirical laws/ where the constancy of the correla- 

 tion is invariable, but the cause is not manifested ; such as that 

 Ruminants alone should have cloven feet and horns on their 

 frontals, concurrently with certain peculiarities in their teeth ': 

 thus establishing a harmony — constant, yet wholly inex})licable 

 — between remote organs apparently unconnected; or, to use 

 the definition of Mr. Huxley, "the invariable coincidence of 

 certain organic peculiarities established by induction." 



Having thus arrived at the general conclusions from observa- 

 tion'on living animals, Cuvier, in the spirit of the same induc- 

 tive philosophy, then applied the inverse process of deduction 

 to the fossil remains : i.e. from the ascertained general, he rea- 

 soned down to the unknown particular, and thus attained those 

 w^onderful results, which have been well characterized by a great 

 living writer as being " among those rare monuments of human 

 genius and labour of which each department of exertion can 

 scarcely ever furnish more than one, eminent therefore above 

 all the efforts made in the same kind*." Throughout his great 

 work there is that continual alternate use of the inductive and 

 deductive method, which, Herschel remarks, is essential to the 

 successful process of scientific inquiry. The case of all others 

 to which he most proudly referred, was the determination of the 

 Eocene Opossum of the Paris basin. The crushed skeleton of a 

 minute quadruped was found in a slab of gypsum, and Cuvier 

 employed the following process of analysis for its identification : 



1. The teeth, and skeleton throughout, indicated a mammifer. 



2. The elevation of the coronoid apophysis above the condyle, 

 and the form of the acute posterior angle of the lower jaw, in- 

 dicated a predaceous animal. 



3. The general construction of the skeleton excluded the 

 Cheiroptera. 



4. The elevation of the condyle above the horizontal line of 

 the teeth eliminated the ordinary Carnivora, such as Dogs, Cats, 

 Martens, &c. ; but was consistent with placental Insectivora, 

 such as the Mole and Hedgehog, and likewise with Opossums 

 and other marsupials. 



5. The molar teeth also were consistent with both placental 

 and implacental Insectivora. 



6. The height and width of the coronoid apophysis, and the 

 peculiar inflection of the posterior angle of the lower jaw, elimi- 

 nated the placental Insectivora, leaving Didelphijs and other 

 marsupials. 



7. Special characters of the teeth excluded all the other mar- 

 supials except Didelphijs and Dasyurus. 



* Brougham, Dissert, vol. ii. p. 113. 



