THE GROWTH OF GROUPS 



145 



there are two types of dermal pattern and three types of 

 shape, six types of fish are possible, of these five are re- 

 presented in this small collection. Of the fifteen possessing 

 the orderly pattern, one is narrow, twelve are medium, 

 and two are broad ; and of the six which are disorderly 

 in the arrangement of the dermal plates four are narrow 

 and two are medium. The broad irregular type which 

 probably exists is not represented in the collection. The 

 five types were found mingled together in the following 

 manner at the four stations or places of capture. 



As shown in the diagrams, the five types are quite 

 distinct ; no one would hesitate in assigning any particular 

 fish to its type. There is, however, one of the regular 

 pattern which cannot be classed either with the medium 

 or with the broad, since it is nearly halfway between the 

 two. No doubt if a large number of individuals had been 

 captured other intermediate specimens would have been 

 found among them, but this is no reason for supposing 

 that the types appear as such because large numbers of 

 such intermediates have been eliminated in the past. 

 We cannot imagine any circumstance appertaining to 

 one locality which would eliminate fish of breadth 60 

 and 80, and leave untouched those of 50, 70, and 90. 



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