Butterfly Migmtions in British Guiana. 157 



noticed crossing the River Aruka about half a mile from 

 Issororo. At 1.10 p.m. I comited in a little over five 

 minutes sixty-two Callidryas, one orange butterfly of about 

 the same size, one smaller yellow species, and two dark 

 Papilio-like insects crossing a space estimated at two hundred 

 yards (moving as our boat moved). They became rapidly 

 more common, and from 1.30-1.35 I counted three hundred 

 and fifty crossing the same estimated distance. They were 

 then for some distance a little less common, but at the 

 junction of the Aruka and the Barima, where we arrived at 

 about 2.15, at least a hundred and fifty per minute were 

 passing. Below this the flight thinned out, and at Mora- 

 whanna, four miles below the junction, scarcely any were 

 to be seen. The course of the rivers is far from straight, 

 but the flight must have been at least five miles across. 

 About one in a himdred of the butterflies was a bright orange 

 species, and a smaller proportion of the dark Papiho-like 

 species ; this latter may, however, have been more common, 

 as it was difficult to see at a distance. 



Catching butterflies while standing up in a small boat 

 is neither easy nor safe, but I managed to net two specimens, 

 one male and one female. 



2nd August. — We left Morawhanna at 11.30 a.m., and 

 were in the migration practically the whole way back to 

 Issororo, where we arrived at 2.30 p.m. The butterflies 

 were occasional near Morawhanna, almost as common as 

 yesterday at the junction of the Aruka and Barima, and 

 frequent all the way up until near the end, when a very 

 hesivj shower sent both us and them into shelter. Even in 

 the thinner parts t^n to twenty per minute were crossing 

 every two hundred yards. To-day I caught five specimens, 

 four males and one female. 



^rd August. — At ten o'clock this morning the yellow 

 butterflies were flying at the rate of two or three per minute 

 past the house (in a clearing about one hundred yards wide 

 and about half-way up a hill about two hundred feet high). 

 At 10.15 none were to be seen ; at eleven o'clock they were 

 again noticed for about five minutes; at 12.30 they were 

 still passing over three or four per minute, and again at 

 two o'clock they were seen occasionally in intervals between 

 showers. At 3 p.m. a few more were noticed. I caught 

 to-day one more specimen, a female. 



Mil August. — At 9.30 a.m. six or seven Callidryas were 

 seen passing south-east over the house; about 11 a.m. they 



