THE SWALLOW-TAIL BUTTERFLY 
347 
the band, the yellow being sometimes obliterated with black. 
The density of the blue powdering of the band is also variable, 
and the red anal spot varies from ochreous-yellow to deep 
Indian-red or dull carmine. In rare instances these spots 
vary in the same specimen, one wing having an ochreous spot, 
while that on the other wing is deep red. Occasionally speci¬ 
mens occur with the ground colour varying from dull ochreous 
to deep cinnamon-buff. 
Although melanic aberrations of P. machaon occur on the 
Continent, no such example was known in this country until 
the year 1921, when a fine black specimen was captured by 
Mr. J. P. Lloyd when fishing in Norfolk. Having no butterfly 
net with him at the time, after several attempts to capture it, 
he finally succeeded in getting his landing net over it and 
secured it. This first-known British example was acquired 
for the Tring Museum. Since that year others have, from 
time to time, been obtained from the same county ; in all, 
about eighteen specimens have made their appearance. It 
is remarkable that this striking black variety should have 
suddenly occurred in Norfolk and become a recurrent aberra¬ 
tion, since it was not known to exist previously in Britain. The 
British type of P. machaon may be readily distinguished from 
the Continental race from the fact that the former is much 
more heavily marked, the marginal bands being much broader, 
the same applying to the costal blotches, giving the insect a 
generally darker appearance owing to the reduction of the 
pale yellow ground colour. 
