ON ABDOMINAL SEGMENTS. 231 



but he gives no figure. In Fig. 8 I have represoLted 

 the junction of the second and third abdominal seg- 

 ments in Lasius flavus, x 225, as shown in a longi- 

 tudinal and vertical section. There are about ten 

 well-marked ribs (r), occupying a length of approxi- 

 mately Yoo ^^ ^^ inch. Similar ridges also occur 

 between the following segments. 



In connection with the sense of hearing I may 

 mention another very interesting structure. In the 

 year 1844, Von Siebold described ' a remarkable organ 

 which he had discovered in the tibicfi of the front legs 

 of Gryllus, and which he considered to serve for the pur- 

 pose of hearing. These organs have also been studied 

 by Burmeister, Brunner, Hansen, Leydig, and others, 

 and have recently been the subject of a monograph by 

 Dr. V. Graber,' who commences his memoir by observ- 

 ing that they are organs of an entirely unique character, 



Fig. 9. 



Tibia of Lasius flwiius g x 75. 



and that nothing corresponding to them occurs in any 

 otlier insects, or indeed in any other Artliropods. 



' See also Sharp, Tram. Ent. Soc, 1893. 



^ l/eber das Stimm. und Gehororgan der Orthopteren, WiegmanrCs 

 Art.f. Nalur., 1844. 



^ Die Tj/mpanalen Sinnesapparate der Orthopteren, Ton Dr. Vitus 

 Graber, IS^S. 



