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BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



to inquire now what particular evidence, if any, melanogaster shows 

 of such consanguinity. Since we are inhibited ])y a lack of speci- 

 mens from determinino; geographic variation, we can expect but 

 little evidence from one form when the two are so very similar. 



Fig. 53.— Distribution of Thamnophis angustirostris melanogaster, as indicated by the 



locality records. 



Specimens of the two forms are so nearly alike both in scutellation 

 and color, that it is impossible to give any character that will always 

 serve to distinguish them; but whether or not we grant that inter- 

 gradation occurs at the present time, I hold it to be quite evident 



