EXTERNAL CHARACTERS PREFERABLE. 247 



well distinguished from each other by external 

 characters, which require no dissection of their 

 mouths ; such a mode of discriminating them is to 

 be preferred before all others, for the best of 

 reasons — as being the most simple and obvious. 

 Nor should we be tempted to employ anatomical 

 characters, or such as are taken from the different 

 modifications in the masticating organs, until we 

 are absolutely compelled to do so by the failure of 

 other resources. This, indeed, is in direct contra- 

 diction to the usual mode of proceeding pursued 

 by modern naturalists ; but, in the present state 

 of natural history, and, indeed, of all science, it 

 appears to us that one of the chief objects of its 

 professors should be as much as possible to simplify. 

 The science they would teach, and which they of 

 course desire that others should learn, can only be 

 rendered inviting to mankind in general, by being 

 divested of all verbose technicality and minute 

 investigation, not absolutely essential. If the same 

 object can be arrived at by two roads — one smooth 

 and comparatively easy, the other intricate, winding, 

 and difficult — no one, in his rational senses, would 

 choose the last in preference to the first. The same 

 analogy should be pursued in science. Simplicity, 

 perspicuity, and brevity should be the characteristics 

 of all systematic distinctions, whether of groups or 

 of species ; and the more we study nature, the more 

 shall we find that in this, as in all other branches 

 of physical science, the laws which are most simple 

 are at the same time the most universal. 



(171.) Essential characters, or such as pre-emi- 

 nently distinguish a group from all others, are 

 R 4 



