( xlii ) 



of the eye to such an extent that no part of its outer surface 

 looked directly forwards. 



" The movements of the flies, after a few minutes, became 

 more active, and they commenced to push their heads against 

 the walls of the cell, protruding the ptilinum as they did so. 

 It was then seen that these movements were made for the 

 pm'pose of discovering a weakness or depression in the wall, 

 and when a fly found such a spot all its efforts were concen- 

 trated there. A fly would push its ptilinum into such a 

 hollow and then alternately expand and contract it, partly 

 rubbing away the mud and partly crumbling it back by pres- 

 sure, and it frequently happened, when one fly gave up the 

 attempt at a particular spot and moved on, that another 

 discovered it and recommenced the work. As a result, the 

 depression became deeper and deeper, and eventually in 

 about an hour a breach was made. The first fly that escaped 

 had a very great squeeze to do so, wriggling through by 

 alternately contracting and expanding its body, and taking a 

 long time. Two others very soon followed it, enlarging the 

 aperture so that those emerging later were able to do so 

 much more readily. 



" The flies that had emerged remained still for about a 

 quarter of an hour, during which the ptilinum was gradually 

 retracted, and not till then did the wings commence to expand. 

 Two or three did not succeed in getting out of the cell till 

 midday, and kept crawlmg about alternately extruding and 

 retracting the ptilinum all the time. One individual did 

 not get out of the cell at all, and by night time its power of 

 pushing out its ptilinum was very much dimmished.'' 



The growth of fungi on the shelters built over 

 CocciDAE BY Cremastogaster ANTS. — Prof. PouLTON gave 

 an account of the following correspondence bearing upon 

 the association between fungi and ants. The first letter 

 was written to Mr. W. A. Lamborn by Mr. C. 0. Farquharson: — 



" Moor Plantation, Ihadan. 



"4:th February, 1914. 



" I am greatly interested in the ant-fungus which you asked 

 me to examine, and more than indebted to you for the op- 

 portimity of studying' it along with ' Wheeler.' Let me say 



