GROUPS FAMILIARLY EXPLAINED. 327 



those with broad bills were referred to the second ; and 

 in neither were habits, analogies, or general structure, 

 taken into the account. On the other hand, we deem a 

 natural group to be an assemblage which is represented 

 by other groups in different classes of animals ; and 

 which is characterised not by one or two peculiarities, 

 but by distinctions drawn both from economy and struc- 

 ture. The toucans, the humming-birds, the lamelli- 

 corn floral beetles, and numerous others, are natural 

 groups, not so much because they are obvious to the 

 inexperienced eye, as because they represent analogically 

 other groups in totally different departments of nature. 

 Strictly speaking, and using the term in its true sense, 

 no group can be termed natural, uxxiW its circular tendency 

 is detected, and its analogical relations pointed out. 



(398.) We are thus led to seek farther information 

 upon the question — How are we to prove that a group is 

 natural? Onenaturalist selects one set of characters, which 

 by another are shghted ; some look only to the internal 

 structure, others confine their characters to the external; 

 and all are prepared with reasons in support of their 

 different theories. How are we then to discover which 

 are the essential requisites or properties of a natural 

 group ? Now, as the series in which natural objects 

 foUow each other is circular, it follows that the circu- 

 larity of a group is its primary requisite. Every group, 

 therefore, which, upon close investigation, does not form 

 its own particular circle, or which does not exhibit a 

 tendency thereto, may be considered artificial ; while, 

 on the contrary, every one which has its affinities re- 

 turning into itself, exemplifies the first general law of 

 nature, and wears the aspect of being natural. 



(399.) The first property, therefore, which we must 

 look for in a natural group, is, that the affinities of the 

 objects it contains proceed more or less in a circle. It 

 is rarely that a group, which from other circumstances we 

 know to be natural, contains so few subjects, and these 

 so wide apart from each other, as to prevent us from 

 detecting their tendency to a circle ; while, on the 

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