The bats were rightly recognised as true ZootoJca, and the 

 genus was defined as Dermaptera. 



The apodal Vivipara, which form the third of Aristotle's 

 more comprehensive groups, embraces the Ketode, now called 

 Cetacea, and affords, by its position and co-ordinates in the 

 great philosopher's zoological system, one of the most striking 

 examples of his sagacity and research. In generalising, how- 

 ever, on modes of reproduction Aristotle includes certain sharks 

 with the cetaceans, distinguishing the former by their gills, the 

 latter by their blow-hole. 



I ought, also, to remark that, although Aristotle has ex- 

 emplified groups of animals which agree with many of the 

 modern Classes, Orders, and Genera, their relative value is not 

 so defined 1 ; and his, in most respects, natural, assemblages 

 would have commanded greater attention and been earlier 

 and more generally recognised as the basis of later systems, 

 had its immortal author more technically expressed an ap- 

 preciation of the law of the subordination of characters ; but 

 Aristotle applies to each of his groups the same denomination, 

 viz. 76^05, genus ; distinguishing, however, in some cases, the 

 greater from the less. 



Centuries elapsed ere any advance was made in the science 

 of Zoology as it was bequeathed to the intellectual world by 

 the mind of Aristotle. Of no other branch of human know- 

 ledge does the history so strongly exemplify the fearful phe- 

 nomenon of the arrest of intellectual progress, resulting in the 

 * dark ages.' The well-lit torch which should have guided 

 to further explorations of the mighty maze of animated nature 

 was suffered to fall from the master-hand, and left to grow 

 dim and smoulder through many generations ere it was re- 

 sumed, fanned anew into brightness, and a clear view re- 

 gained both of the extent of ancient discovery and of the 

 right course to be pursued by modern research. 



1 See the just and discerning remarks on this subject by Dr WHEWELL, in 

 hia admirable History of the Inductive Sciences, 3rd ed., Vol. in. p. 289. 



B2 



