( cliv ) 



neath the abdomen as membranous extensions, which meet 

 in a suture along the middle line, or sometimes even overlap 

 one another. Between them and the true ventral surface of 

 the abdomen a cavity is formed which is filled with air; and 

 it is into this air-chamber that the spiracles open. A median 

 triangular lobe arising from the sternite of the 2nd segment 

 fits in between the lobes of the 3rd segment, and together 

 with a ridge extending from it on each side, closes up the 

 air-chamber in front. Air can be admitted to, or expelled 

 from, the chamber by means of a Y-shaped slit or valve, 

 formed where the lobes of the 9th segment and the anal lube 

 come together. Fab re in his account of the froth insect 

 (" Souvenirs," 7th Ser. 1900) had noticed this Y-shaped slit 

 at the end of the abdomen, and correctly observed that it 

 was by means of this valve that it blows its bubbles; but 

 this was about the only accurate observation in his account, 

 which for the rest must be treated as mainly conjectural or 

 imaginary. Kershaw, in a paper in " Psyche " for 1914, had 

 described the structure of the abdomen in the case of another 

 species of Cercopidae, but whether for the first time or not, 

 he was at present unable to say. Kershaw, however, main- 

 tained that the air which fills the bubbles was expelled along 

 with the liquid from the alimentary canal, thus upholding 

 the view which has been generally accepted since the time 

 of De Geer; and he believed that the chief function of the 

 air-chamber was to keep the spiracles from being clogged by 

 the froth which surrounds the insect. The President said he 

 was convinced from his own observations, confirmed by those 

 made by Mr. F. Muir at his invitation, that there was no air 

 mixed with the liquid as it issued from the anus; that the 

 air with which the bubbles of froth were blown was forced 

 out from the air-chamber beneath the abdomen through the 

 Y-shaped slit at its end. Glands at the sides of the 7th 

 and 8th abdominal segments from which tufts of white fila- 

 ments extend had been variously interpreted, Berlese con- 

 sidering them to be the source of the liquid secretion, and 

 Prof. Porta as a combination of wax-glands and tracheal 

 gills; but as he found that the white tufts were completely 

 dissolved in ether, he believed the glands were simply wax- 



