214 THE entomologist's RECORD. 



mimerous examples appeared in the chart-room and cabins of the 

 P. and 0. steamer "Victoria." At the time the nearest land to the 

 vessel was " Keehng Island, N,, 20 W., 290 miles, N.W. of Australia, 

 S., 70 E., 900 miles." At the time the wind was moderate from east- 

 ward, with heavy rain. McLachlan adds that this record "is of 

 especial interest, not only on account of the great distance from the 

 nearest land, but also because the " insects were observed at night and 

 during heavy rain." The power of continued flight suggested by this 

 observation is sufficient to explain the distribution of the species over 

 the whole intertropical zone, and far beyond it on either side, and yet, 

 notwithstanding its considerable size, it appears to be an insect of 

 weak organisation, the chitinous exoskeleton being of thin texture. 



It may be well to note here that when Mathew visited the estuary 

 of the river Ouro, on the West (!oast of Africa, lat. 23° 40' N., in 

 December, 1881, he found a large dragonfly, Auax ephippii/cr, in the 

 greatest profusion, although there was no sign whatever of fresh Avater 

 in the neighbourhood, nor had there apparently been any rain for 

 many months. These dragonflies flew oil" to the ship in considerable 

 numbers, and at night might be seen reposing on the various ropes, 

 whilst shortly before dusk, on the sand ridge at the mouth of the 

 estuary, they were noticed congregating in vast numbers on the bushes. 

 Although the estuary was explored for SDme twenty miles or more 

 inland, there appeared to be no sign of fresh water, and it would 

 appear that the Ouro was a river in name only. Fj/ranwis canlui, 

 CItocrocampa cderio, and Hcliothis anitiper were (besides an Agrotis 

 resembling rijiac) the only Lepidoptera observed. 



In La Plata the pale blue ^Esclina bu)iafieHsis frequently occurs on 

 the pampas in enormous flocks, which usually appear just in advance 

 of the violent storm-wind called the " pampero." In the Nattoalist in 

 La Plata we read: — " Inasmuch as these insects are not seen in the 

 country at other times, and frequently appear in seasons of prolonged 

 drought, when all the marshes and water-courses for many hundreds of 

 miles are dry, they must of course traverse immense distances, flying 

 before the wind at a speed of seventy or eighty miles an hour .... 

 As a rule they make their appearance from five to fifteen minutes 

 before the wind strikes ; and when they are in great numbers the air 

 to a height of 10ft. or 12ft. above the surface of the ground is all at once 

 seen to be full of them, rusliing past with extraordinary velocity in a 

 north-easterly direction .... All journey in a north-easterly 

 direction, and of the countless millions, flying like thistle-down before 

 the great pampero wind, not a solitary traveller ever returns." These 

 flights occur during the summer and autumn, and Mr. Hudson thinks 

 the cause " is probably dynamical, aftecting the insects with a sudden 

 panic, and compelling them to run away before the approaching 

 tempest. The mystery is that they should fly from the wind before it 

 reaches them, and yet travel in the same direction with it ... . 

 On arriving at a wood or large plantation they swarm into it as if 

 seeking shelter from some swift pursiiing enemy, and on such occa- 

 sions they sometimes remain clinging to the trees while the wind 

 spends its force." Walker states tliat in the estuary of the Rio de la 

 Plata the sight of numbers of dragonflies (often met with when the 

 land is so far oft" as not to be visible) is always regarded by the local 

 mariners as the harbinger of a " pampero," and measures are taken 



