THE MIGRATION OF BUTTERFLIES. 335 



The Black-throated Diver (Colymbus arcticus) was very 

 numerous, and served us as a good weather prophet. We obtained 

 two eggs of this species on June 29th from an island in a small 

 lake called Tauki-jarvi, near Keinovuopio. The Red-throated 

 Diver (C. septentrionalis) was less numerous, but fairly common 

 near Kaaresuando. We obtained one egg on June 16th from an 

 island in the rapids called Karjalakoski. 



THE MIGRATION OF BUTTERFLIES. 

 By the Editor. 



In the month of April last Mr. T. J. Mann, who was then 

 sojourning in Ceylon for the benefit of his health, sent me a 

 small collection of butterflies captured at Navanghena, with the 

 following interesting note : — 



" In this island, during the months of March and April, there 

 is a vast migration of butterflies from N.E. to S.W. They appear 

 not merely in hundreds, but in thousands, perhaps millions. This 

 movement of countless numbers all going in one direction, as of 

 set purpose, was first noticed this year about March 15th in the 

 northern part of the island; and at a moist spot in the otherwise dry 

 bed of a river, where they had apparently alighted to get moisture, 

 the ground was quite white with their wings, reminding one of 

 what one sees at home under the hawthorn trees when, after a 

 sharp shower, the ground is strewn with may-blossoms. The 

 migration, for such it appeared to be, commenced about 7 a.m., 

 and lasted until noon, when there was a lull, or temporary 

 cessation of flight, after which the movement recommenced, and 

 the insects continued to pass on in swarms as before. I send you 

 a series of specimens for identification ; they will probably prove 

 to be males and females of one species, and no doubt you will be 

 able to name them, or get them named. I may add that large 

 numbers of apparently the same butterflies were observed by 

 friends one hundred miles out at sea to the S.W. of Ceylon." 



On receipt of this note I at once took steps to identify 

 the species from the specimens sent ; and with the aid of Mr. 

 F. Moore's beautifully illustrated work on the Lepidoptera of 

 Ceylon, and the assistance of Dr. A. G. Butler, who kindly 



