66 THE BUTTERFLIES OF THE BRITISH ISLES. 



there are, as a rule, no blue crescents in the hind marginal 

 border, but there is an extra black spot placed between veins i 

 and 2 ; on the hind wings a black spot on the front area 

 represents the black basal area seen on the Small Tortoise- 

 shell ; and this is an important point of difference, although the 

 two species are not likely to be confused when both are well 

 known. The blue spots referred to as not usually present on 

 the fore wings are stated to occur in specimens emerging from 

 chrysalids that have been kept in a rather cold temperature for 

 a certain length of time. 



An aberration known as testudo has the black spots of the 

 fore wings united, and forming blotches on the front and inner 

 areas ; the ground colour of the fore wings is lighter, and the hind 

 wings are blacker. This form occurs at large on the Continent, 

 but it is rare ; it has also been produced in the course of 

 temperature experiments. 



The only eggs of this butterfly that I have been able to obtain 

 are the batch figured on Plate 34. These were purplish with 

 whitish ribs, but no caterpillars hatched from them. Hellins, 

 who squeezed a few eggs from a freshly killed female, states 

 that the colour apparently is a dull green. The ribs vary from 

 seven to nine in number. 



The caterpillar in the adult stage is black, with a speckled 

 dark ochreous band traversed by a black central line on the 

 back ; the sides are dappled with ochreous grey ; the under 

 parts are brown dappled with darker, and merging into the 

 black. The spines are dark ochreous tipped with black, and 

 the head is shiny black and bristly. (The figure is after Buckler.) 



These caterpillars live in large companies, often at the top of 

 a high elm tree, from which they may be dislodged by a well- 

 aimed stick, if this happens to be heavy enough to jar the 

 branch when it reaches the mark. Besides elm trees {Ulmus), 

 they also may be found on willow and sallow (Sa/ix), aspen 

 and poplar (Popidus), white-beam (Pyrus aria), and various 



