22i [October, 



flew from plant to plant from S.S.E. to N.N.W. Next day they had 

 disappeared ; but a few apparently remained, for since that time 

 several have been seen, where there were none formerly." 



" The temperature was very high during the two migrations, and 

 especially on the 11th and 12th. In the interval a fall of the ther- 

 mometer took place. Here are the maxima and minima observed at 

 TJccle on the 4th, 5th, 10th, Uth and 12th June." 



Max Mm. 



4th 26-9 Cent. = 80-6 F 14-3 Cent. = 577 F- 



5th 26-0 „ = 78-8 „ 13-4 „ = 56-1 „ 



10th 27-0 „ =: 80-6 „ 120 „ = 53-6 „ 



11th 30-6 „ = 871 „ 16-3 „ = 61-3 „ 



12th 31-0 „ = 87-8 , 15-7 „ = 60-2 „ 



" It is noticeable that the nights were very warm. On the 5th 

 the heat was already great at 7 a.m. when the first Dragon-flies were 

 seen, and it increased rapidly." 



" After having given particulars of the circumstances in which 

 these migrations were accomplished, and some of their principal pecu- 

 liarities, we find ourselves confronted by a mark of interrogation, a 

 veritable enigma and difiicult to solve. Whence came these swarms 

 observed in Belgium at the commencement of June ? Where did they 

 originate ?" 



" So far as concerns the migration of the 10th to 12th the reply 

 does not appear doubtful : they came from the sea. But did they 

 come from England or the open sea ? In England no mention has 

 been made of migrations, and their presence in our country (Belgium) 

 remains unexplained." 



" It is not to us doubtful that the swarm observed in Belgium on 

 June 5th, after having voyaged over the open sea to the North, and 

 at several hundreds of kilometres from the continent, not finding any 

 issue to its long journey northwards, turned tail, and followed the 

 same route by which it went, the most vigorous of the survivors re- 

 gaining the earth on the 10th, the weaker three days afterwards." 



[There are indications that part of this same swarm reached 

 England, not that it originated in England. — E. McLachlan]. 



" All the facts tend to arrive at the following conclusion. The 

 Dragon-flies observed in Belgium on the 5th came from regions situ- 

 ated to the east of the country, which they entered in several columns 

 flying at a great altitude ; between 7 and 8 a.m. they descended 

 towards the earth, continuing their route towards the west. But we 

 remain in ignorance of their point of departure, for from Germany 

 we have not been able to collect the slightest information ; in fact. 



