Mr. H. Seebohm on the Genus Scolopax. 141 



Scolopax gallinago. Scolopax wilsoni. 



Tail-feathers fourteen in number. Tail-feathei's sixteen in number. 



Axillaries white. Axillaries transversely barred with 



broad dark bands. 



Breast witli obscure dark lonyitii- Breast with obscure dark transverse 



dinal streaks. bars. 



Bill varying from 2'8 to 2'o inches Bill varying from 2'7 to 23 inches 



iu length. in length. 



Outer tail-feather crossed by three Outer tail-feather crossed by Jioe 



dark bars. dark bars. 



So far as I know, the American birds are always constant 

 to their characters ; but, unfortunately for the validity of the 

 two species, there is not one of these characters (except per- 

 haps the very short bill, which is not always characteristic 

 of the American form) which does not frequently occur in 

 examples from the Old World. Hume says that in India 

 Fan-tailed Snipes with sixteen tail-feathers are common 

 enough. Snipes with barred axillaries are perhaps the rule 

 rather than the exception, even in England. Snipes with 

 transversely- barred breasts are occasionally found in the Old 

 World, and the number of bars across the outer tail-feathers 

 of British-killed examples varies from three to five. Never- 

 theless, I have never seen an Old- World example of a Snipe 

 possessing all the characters of the American species. 



It is easy to suggest a reason why the Nearctic Common 

 Snipes should vary less than the Palsearctic Common Snipes. 

 During the luterglacial period preceding the Glacial period 

 (probably the last of the series), which more or less differ- 

 entiated these two forms, they were presumably a circum- 

 polar species. The gradual accumulation of ice at the North 

 Pole gradually drove the species south, and soon isolated the 

 Nearctic from the Palsearctic birds. Isolation was followed 

 by its usual concomitant — differentiation, and the imjiossi- 

 bility of interbreeding caused the two groups to become at 

 least subspecifically distinct. The conformation of the 

 American continent did not prevent constant intercourse in 

 their temporary quarters in the south ; consequently, what- 

 ever changes took place in the species became common pro- 

 perty. On the other hand, in the Old World, the Snipes 



