10 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [NoV. 5, 



speculations as to the ease and possibility with which such hoofed 

 quadrupeds might ride down and slay another animal. A domesti- 

 cated recalcitrant animal may disable or kill his master by a blow 

 of the hoof, but he does not therefore devour him. 



The truth or fact of a physiological knowledge of the condition of 

 a correlated structure and of the application of that knowledge to 

 Palseontology is not affected or destroyed by instances adduced from 

 that much more extensive series of coincident structures of which the 

 physiological condition is not yet known. Nor is the power of the 

 application of the physiologically interpreted correlation the less cer- 

 tain, because the merely empirically recognized coincidences have 

 failed to restore, with the same certainty and to the same extent, an 

 extinct form of animal. 



Certain coincidences of form and structure in animal bodies are 

 determined by observation. 



By the exercise of a higher faculty the reason, or a reason, of these 

 coincidences is discovered and they become correlations ; in other 

 words, it is known not only that they do exist, but how they are re- 

 lated to each other. 



In the case of coincidences of the latter kind, or of "correlations " 

 properly so called, the mind infers with greater certainty and con- 

 fidence, in their application to a fossil, than in the case of coinci- 

 dences which are held to be constant only because so many instances 

 of them have been observed. 



Because the application of the latter kind of coincidences is limited 

 to the actual amount of observation at the period of such application, 

 and because mistakes have been made through a miscalculation of 

 the value of such amount, it has been argued that a rational law of 

 the correlation of animal forms is inapplicable to the determination 

 of a whole from a part * ; and it has not only been asserted that the 

 results of such determination are unsound, but that the philosopher 

 who believed himself guided by such law deceived himself and mis- 

 conceived his own mental processes ! But the true state of the case, 

 as I believe it to be apprehended by the working palaeontologists 

 since Cuvier's day, is, that the non-applicability of his law in certain 

 cases is not due to its non-existence, but to the limited extent to 

 which it is understood. 



The consciousness of that limitation led the enunciator of the law 

 to call the attention of palaeontologists expressly to the extent to 

 which it could then be applied, as, for instance, to the determination 

 of the class, but not the order, or of the order, but not the family or 

 genus, &c. ; and to caution them also as to the extent of the cases in 

 which, the coincidences being only known empirically, he conse- 

 quently enjoins the necessity of further observation, and of caution 

 in their induction. Cuvier expresses, however, his belief that such 

 coincidences must have a sufficient cause, and that cause once dis- 

 covered, they then become correlations and enter into the category 

 of the higher law. Future comparative anatomists will have that 

 great consummation in view, and its result, doubtlessly, will be the 



* De Blainville, op. cit. p.- 34. 



