ON ABDOMINAL SEGMENTS. 231 



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

 the junction of the second and third abdominal seg- 

 ments in Lasius fiavus, 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 -Ywu of ^^ inch. Similar ridges also occur 

 between the following segments.' 



In connection with the sense of hearing I may men- 

 tion another very interesting structure. In the year 

 1 844, Von Siebold described * a remarkable organ which 

 he had discovered in the tibiae of the front legs of 

 Gryllv^, and which he considered to serve for the pur- 

 pose of hearing. These organs have been also studied 

 by Biu-meister, Brunner, Hensen, Leydig, and others, 

 and have recently been the subject of a monograph 

 by Dr. V. Grraber,^ who commences his memoir by ob- 

 serving that they are organs of an entirely unique cha- 



Fig. 9. 



X 



Tibia of Lasvutflavus $ x 75. 



racter, and that nothing corresponding to them occurs 

 in any other insects, or indeed in any other Arthropods. 



» See also Sharp, Trans. Ent. Soc, 1893. 



» Ueler das Stimm. und Gehor organ der Orthopteren, Wieg- 

 mann's Art.f. Natur., 1844. 



' Die Tymjxvnalen Sinnesapparate der Orthopteren, von Dr. Vitua 

 Graber. 1875. 



