xcii. PRESIDENT'S ADDRESS. 



volcanic dust in the eruptions of Krakatoa and others is even 

 more remarkable. 



NEUROPTERA. 



The migratory tendency is well developed amongst the 

 Odonata or dragon flies, especially in some species, and many 

 cases have come under observation. Libellula quadrimaculata, 

 one of the larger British species, which is found also in many 

 other parts of the N. temperate zone, is one of the most frequent 

 migrants in this group. One interesting account of such a 

 migration is as follows (abridged from "Nature," July ipth, 

 1883) : On Sunday, June 24th, 1883, at Malmo, in Sweden, the 

 dragon flies passed over for about half-an-hour in the afternoon. 

 The next day, about one o'clock, they re-appeared for more 

 than an hour ; but on Tuesday, the 26th, at 7.30 a.m., they 

 again began in millions, and, notwithstanding the wind had 

 shifted to the south during the night, they held the same course 

 of S.E. by E. The streets, shipping, and every place were full 

 of them. They did not fly very high, and seemed to avoid going 

 into the open doors and windows, but alighted on the trees. 

 The flight ended that night at 8 p.m., having been incessant for 

 more than twelve hours. On the 27th they appeared again at 

 noon in reduced numbers, and a few on successive days after- 

 wards, the migration ceasing with the advent of hot weather. 

 Other flights have been recorded off the Essex coast on 

 June 23rd, 1888, in Heligoland on May 2ist and 22nd, 1889, all 

 disappearing on the 26th with a change of wind to northerly, 

 and on June 6th of the same year a small flight at Dover. A 

 large migration of this species is said to take place yearly from 

 N. to S. in the Charente Inferieure, in France. Another species 

 which has the migrating habit is Libellula depressa known in 

 this neighbourhood and probably elsewhere as the "horse- 

 stinger," though it is, of course, destitute of any sting. A 

 compact band passed over Konigsburg in June, 1852, 60 feet 

 wide and about 10 feet deep, and from the details given must 

 have extended for a length of 60 or 70 miles. 



