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The gregarious habit during Hibernation of Musca 

 CORVINA, F. — Prof. PouLTON described the hibernation of 

 vast numbers of M. corvina in the cistern-loft of St. Helens 

 Cottage, St. Helens, Isle of Wight. When he arrived at 

 St. Helens on Jan. 4, 1915, it was found that a most unpleasant 

 smell was emitted by the low-pressure water-supply, both hot 

 and cold. He investigated the loft on Jan. 5 and found 

 several patches of flies on the close boarding of the roof. 

 The angle between a rafter and the boarding was nearly 

 always selected as a resting-place where the flies were crowded, 

 touching each other, so as to form long narrow black patches. 

 Part of one small patch was resting on the floor, the remainder 

 passing out of sight over the edge of the floor-boarding. Each 

 of the largest assemblages must have included many hundreds 

 of individuals. Many dead mould-covered flies were floating 

 in the two coupled cisterns, while far larger numbers were lying 

 thickly spread over the bottom. One cistern, which happened 

 to stand beneath the most crowded part of the roof was far 

 more affected and smelt more strongly than the other. When 

 the water was turned off and the cisterns emptied from the 

 taps in the lower part of the house one ball-tap became choked 

 with flies and had to be taken apart in order to clear the 

 obstruction. The body of water affected was large, being 

 13f in. deep in both cisterns, the internal length and breadth 

 of the most strongly affected 34 in. and 17 in., of the other 

 331 in. and 21 f in. respectivel3^ To this must be added the 

 quantity of water in the pipes, the cylinder of the hot-water 

 apparatus, and four flushing cisterns. A large sample of the 

 semi-torpid flies was taken by the simple process of sweeping 

 part of the roof with an ordinary housemaid's brush into a 

 pail of hot water. It was observed that the great majority 

 of the flies sank to the bottom a few hours after they had 

 been killed by the heat. The sample after being dried was 

 sent to Col. J. W. Yerbury, who very kindly determined and 

 sexed the specimens exhibited to the meeting, viz. 304 males 

 and 514 females, not including 23 specimens, mostly in very 

 poor condition, which could not be determined with confidence. 

 Mr. A. H. Hamm had kindly assisted in counting the speci- 

 mens and arranging the exhibit. Col. Yerbury had agreed 



