CLASS OF FISHES. 359 



even of genera, yet strongly resembling each other in dif- 

 ferent regions of the globe, I have thought that the following 

 brief sketch of the relation of species to genus might interest 

 the reader : 



" Zoology, to be esteemed a science, must be based on philo- 

 sophical principles. True, it is a science of observation and 

 not of calculation ; it has to deal with living bodies, and with 

 the mysterious and hitherto undiscovered principle of life, 

 whose laws are not to be explained by numbers, however 

 multiplied, nor by a geometry, however refined. Fluxions 

 avail not here, nor the integral calculus. Nevertheless, some 

 great minds have shown that Zoology has its laws, which, 

 despite difficulties almost innumerable, may be so inquired 

 into as to evolve some truths of more import to man than at 

 first appears. 



" The observation of nature is no doubt the first duty of 

 every candid observer ; next comes the duty of the inquirer 

 into her laws, for the mere observance of a fact is of no value 

 whatever, unless that fact be placed in its relations with all 

 others. Men had observed, and no doubt observed carefully, 

 long before the age of Aristotle, but he alone was equal to the 

 production of the Historia Animalium. He was followed, 

 at a long interval, by Buffon and Linne ; last came the im- 

 mortal Cuvier. The discovery of the true signification of the 

 fossil remains of the organic world by this illustrious and 

 justly celebrated man, was unquestionably the most remark- 

 able step ever made for the advancement of the human mind. 

 The element of research he employed was the descriptive 

 anatomy of the adult or fully-developed individual of all, or 

 at least of most, of the species of animals now occupying the 

 globe. The minute descriptive anatomy of the species, with 

 a view to the rigorous determination of its true nature and 

 position in a natural-history arrangement, seemed to be the 

 ultimatum of all his inquiries ; and if he spoke of genera or 

 natural families, it was more as a naturalist, or as one by 

 whom generic distinctions were viewed rather as expressions 

 of philosophic arrangement than as realities based in Nature. 

 It was whilst pursuing this inquiry into the existing and 

 living fauna of the present world, that the- thought struck 

 him of applying the element of research he then wielded with 

 such dexterity to the fossil remains of a former world : never 

 since man studied science had a thought so fruitful in great 

 results entered the human mind. By it he dissected, as it 



