148 THE DISPERSAL OF SHELLS. 



It is perhaps worth while in this connection to notice 

 an extraordinary fall of oak leaves, witnessed in 1889, 

 in Dumfriesshire, on a farm on which were only five 

 trees (two ash and three larch) ; the following account 

 of the occurrence, in the words of the observer, was 

 published in Nature in 1890: ^ 



" I was struck by a strange appearance in the at- 

 mosphere, which I at first mistook for a flock of birds, 

 but as I saw them falling to the earth my curiosity was 

 quickened. Fixing my eyes on one of the larger of them 

 and running about a hundred yards up the hill until 

 directly underneath, I awaited its arrival, when I found 

 it to be an oak leaf. Looking upwards the air was 

 thick with them, and as they descended in an almost 

 vertical direction, oscillating, and glittering in the sun- 

 shine, the spectacle was as beautiful as rare. The 

 wind was from the north, blowing a very gentle breeze, 

 and there were occasional showers of rain. On ex- 

 amination of the hills after the leaves had fallen, it was 

 found that they covered a tract of about a mile wide 

 and two miles long. The leaves were wholly those of the 

 oak. No oak trees grow in clumps together nearer than 

 eight miles. The aged shepherd, who has been on the 

 farm since 1826, never witnessed a similar occurrence." 



Mr. Musson, writing from Sydney, tells me that the 

 dry-weather molluscs of that region hide under twigs, 

 logs, and scraps of wood, sestivating in many cases, so 

 that they are almost certainly transported with the tre- 



^ J. Shaw, quoting a letter received fi-om Mr. Wright, " Nature,'' 

 xlii. (1890), p. 637. 



