390 HISTORY OF ZOOLOGY. 



a principle. But the doctrine of a relation of 

 Analogy distinct from Affinity, in the manner which 

 has recently been taught, seems to be obviously at 

 variance with that gradual approximation of the 

 classificatory to the physiological sciences, which 

 has appeared to us to be the general tendency of 

 real knowledge. It seems difficult to understand 

 how a reference to such relations as those which 

 are offered as examples of analogy 14 , can be other- 

 wise than a retrograde step in science. 



Without, however, now dwelling upon these 



points, I will treat a little more in detail of one 



L 



of the branches of Zoology. 



14 For example, the goatsucker has an affinity with the 

 swallow ; but it has an analogy with the bat, because both fly 

 at the same hour of the day, and feed in the same manner. 

 Swainson, Geography and Classification of Animals, p. 129. 



