Butterfly Migrations in British Guiana. 339 



case of observation No. 6 it seems very unlikely, for not 

 more ttan a couple of animals pass along this road each 

 day. It would seem more hkely that, apart from the 

 natural gregarious habits of these insects, the object of 

 such swarnung would be to obtain a certain amount of 

 heat and dryness, conditions that are almost impossible 

 to obtam m the forest except in such places where the swarms 

 were observed. 



The observation on Catopsilia statira is interesting on 

 account of its locahty, while that of Pieris phileta is notable 

 for its density. 



In conclusion I wish to express my thanks to those 

 gentlemen, and especially to Mr. Winter, who have so kindly 

 allowed me to make use of their observations. 



Explanation of Map. 



Sketch map of British Guiana showing locaHties where migrations 

 or unusual numbers of butterflies were seen. For detailed explana- 

 tion of signs used see Trans. Ent. Soc. Lond., 1919, p. 77 and PI 

 VI the arrowheads indicating direction and extent of migrations" 

 and the crosses the scale of abundance of the insects at rest. 



