574 



HEMIPTERA-HOMOPTERA 



structures. In order to see the parts it is better to cut away 

 an opereulmn ; underneath it three membranes can be seen, an 

 external, the tinibal ; an anterior, the folded or soft membrane ; 

 and a posterior, the mirror. This last is a most beautiful object, 

 tensely stretched and pellucid, yet reflecting light so as to be 

 of varied colours ; there are also three stigmata, and some 

 chambers connected with the apparatus. The sound is primarily 

 produced by the vibrations of the timbal, to which a muscle is 

 attached ; the other membranes are probably also thrown into a 

 condition of vil:)ration, and the whole skeleton of the Insect helps 

 to increase or modify the sound, which is probably also influenced 



,nt"'-P^ St 



Fia. 281. — Musical apparatus of CicaAa plebeia. (After Carlet.) A, Ventral view (Oper- 

 culum on right side is removed) ; cqj, apophysis ; C, cavern ; c, trochantiu (clieville 

 of Reaumur) ; ent, part of internal skeleton of abdomen ; mi, specular membrane ; 

 m.pl, soft or folded membrane ; p, base of leg ; st, st' , st", stigmata ; t, drum 

 " tinibale " ; v, operculum ; 1«, tirst, 2a, second abdominal segment : B, same seen 

 laterally, portion of abdominal wall as well as operculum removed ; a. point of 

 insertion of hind wing ; Mes, mesothorax ; sc, scutum of metathorax : 3h, third 

 abdominal segment : rest as in A. 



by the position of the opercula. The stigmata ^^robably play an 

 important part by regulating the tension of the air in the 

 chambers. In the female some of the structures are present in 

 a rudimentary form, but there are no muscles, and this sex 

 appears to be really quite voiceless. 



Fam. 2. Fulgoridae. — Ocelli two (rarely/ three, or entirely 

 ohsolete), 2>^((ced hcneath the eyes or near the eyes, vsiuilly in 

 cavities of thecheels, antennae j^lnced heneath the eyes, very variable 

 inform; nsually of two joints terminated by a very Jine hair, 

 the second joint taith a fectdiar texture of the surface, oxoiny to the 

 existence of sensitive structures (Hansen). Form of head very 

 diverse ; vertex and face forming either a continuous curve, or the 

 planes of the vertex and face forming an acute angle, or both pro- 



