141 
Mr. H. Seebohm on the Genus Scolopax. 
Scolopax gallinago. 
Tail-featliers fourteen in number. 
Axillaries white. 
Breast with obscure dark longitu¬ 
dinal streaks. 
Bill varying from 2 # 8 to 2’5 inches 
in length. 
Outer tail-feather crossed by three 
dark bars. 
Scolopax ivilsoni. 
Tail-feathers sixteen in number. 
Axillaries transversely barred with 
broad dark bands. 
Breast with obscure dark transverse 
bars. 
Bill varying from 2*7 to 2 3 inches 
in length. 
Outer tail-feather crossed by Jive 
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 Interglacial 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 impossi¬ 
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 
