Elgee: The Driftless Area of North-East Vorkshtre. 141 
no forms are met with either in Iceland or Spitzbergen, although 
upwards of three hundred species of insects are represented in 
the former.’ 
Among the Coleoptera several distinctly northern and Alpine 
species now existing in North Yorkshire in all probability lived 
within the ice free region, e.g., Pterostichus aethiops and P. 
vitreus, both Alpine species ; and Miscodera arctica, recorded by 
Mr Lawson Thompson, from Stanghow Moor. Doubtless 
others have survived, especially those which live on the moor- 
land plants, such as Haltica ericett, Ceuthorhynchus erica, etc. 
If these northern and Alpine species lived in sheltered places 
on the uplands during the Ice Age, it does not follow that no 
southern forms managed to struggle through thereon. If, as 
the Ice Age progressed, any species of southern origin con- 
trived to escape on the driftless area, we ought still to find 
them either on the region itself or, allowing for dispersal since 
the close of the Glacial Period, just outside its bounds. The 
evidence, too, would be complete if the species also occurred in 
the south of England, but not in the intermediate area. 
Although such a case seems highly improbable, yet we actually 
have one in the Solitary Ant (WutZla europaea), of which two 
specimens have been discovered in East Yorkshire, the first by 
Mr. Hey in 1903; and the second by myself in 1904.* 
As this insect is a rare and interesting species, it will be 
worth our while to dwell a little longer on its geographical 
distribution, and see by what means it has arrived in East 
Yorkshire. Before the above records were made, the most 
northern locality for MJutilla europaea, according to Mr. 
Saunders, was Colchestsr in Essex ; nor since his great work 
on the Hymenoptera Aculeata of Britain appeared, have any 
except the Yorkshire examples been found north of that town 
(as he informs me in answer to a letter I wrote asking if such 
were the case). 
We have here a very remarkable example of discontinuous 
distribution within our island, but before attempting an explana- 
tion of it we must glance at the further distribution of the 
species in England and Europe. In England it occurs 
principally in the sandy regions of Surrey, Dorset, Hampshire, 
and Berkshire, whilst on the Continent it is found in Sweden, 
Finland, Russia, Austria, Germany, and Italy. 
If now we examine the distribution of the genus Mutilla in 
OO 
; * ‘Naturalist,’ 1903, p. 455; and 1GO5, p. 4o. 
1¢go7 April 1, 
