14 THE ENTOMOLOGIST. 



So far as I know, this insect has not occurred in England since 

 1903, when Mr. Boyd took a single female in Cornwall (' Ent. 

 Month. Mag.,' vol. 39, p. 201). 



On July 29th I thought I saw another male at Aldenham, 

 but I could not capture the insect. 



Lihellida depressa, Linn., was very common this year. A 

 mature male was caught at Burnham Beeches on June 23rd 

 while at rest on a tyre of my bicycle which was lying on the 

 bank of one of the ponds there. On June 21th it was exceedingly 

 abundant at Shenley, Herts. I distinctly saw a male and 

 female in Ogwen Lake Valley, Carnarvonshire (North Wales) on 

 June 25th. On July 12th I took a female near Shenley which 

 showed obvious signs of blue powder on the abdomen. The last 

 specimen taken was a blue female on August 4th near Tunbridge 

 Wells, in Sussex. 



L. quadrimaculata, Linn., has also been very abundant, and 

 there are possibilities of a migration having taken place. It was 

 observed in great numbers in June at the Capel Curig lakes, in 

 North Wales, and many immature specimens were caught. 

 Near Tunbridge Wells it was very common at the beginning of 

 August. Having heard of a migration of dragonflies round 

 Alderney, I at once communicated with my friend Sir William 

 Parker, in the Isle of Wight, and he took a specimen of this 

 species (the only dragonfly he saw), which has very little wing 

 coloration, but it is not justifiable to assume that it was one of 

 the swarm from Alderney. 



The wing-suffusion in many specimens from North Wales 

 was greatly marked, whereas many from Sussex had very little 

 colouring on the wings, showing that there is no foundation in 

 the theory that in more northerly regions the wing-suffusion is 

 diminished, and in more southerly extended. 



When on the wing I have repeatedly noticed that this 

 dragonfly appears of a bright blue colour, and resembles the 

 mature male of L. depressa very closely. This is probably due 

 to the reflection of light from the abdomen of L. quadrimaculata, 

 and is doubtless a case of two insects obtaining a similar colour- 

 effect by different means ; but the question as to whether the 

 colour of both species is protective, or whether there is mimicry 

 between the two insects, presents a problem difficult of solution, 

 especially when regarding two animals so well equipped against 

 the dangers which arise in their struggle for existence. 



Orthetrum ccendescens, Fabr., was very common on August 

 4th and 5th in a marsh near Tunbridge Wells. The insect did 

 not fly very fast, and was not difficult to net. I took several 

 specimens with very dark wings, and there was a very wide 

 range in the size of the male. 



0. cancellatuni, Linn. — Two specimens of this uncommon 

 insect were obtained at the Aldenham Eeservoir (Herts), a much 



