416 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1923 



volume of the sound, however, are probably in large part due to 

 the vibration of the thin basal membranes of the wings, which are 

 called the tympana (Tm). 



^he instruments of different players differ somewhat in the details 

 of their structure. There are variations in the form and size of 

 the file and the scraper on the wings of different species, and 

 differences in the veins supporting the tympanal areas, as shown in 

 the drawings of these parts from a conehead (fig. 13) given at A, B. 



and C, of Figure 6. In the 

 true katydid, the greatest 

 singer of the family, the 

 file, the scraper, the tym- 

 pana, and the wings them- 

 selves (fig. 12) are all very 

 highly developed to form 

 an instrument of great effi- 

 ciency. But, in general, the 

 instruments of different 

 species do not differ nearly 

 so much as do the notes 

 produced from them by 

 their owners. An endless 

 number of tunes may be 

 played upon the same 

 fiddle. With the insects 

 each musician knows only 

 one tune, or a few simple 

 variations of it, and this he 

 inherited from his ances- 

 tors along with a knowl- 

 edge of how to play it on 

 his inherited instrument. 

 The stridulating organs are 

 not functionally developed 

 until maturity, and then the insect forthwith plays his native air. He 

 never disturbed the neighbors with doleful notes by practicing. 



Very curiously none of the katydids nor any members of their 

 family have the earlike organs on the sides of the body possessed 

 by the locusts. What are commonly supposed to be their organs of 

 hearing are located in their front legs, as are the similar organs of 

 the crickets. Two vertical slits on the upper parts of the shins or 

 tibiee (fig. 6, D, e) open each into a small pocket with a tympanum- 

 like membrane stretched across its inner wall. Between the mem- 

 branes are air tubes and other structures, to be described later along 



Fig. 6. — Sound-making organs and the " ears ' 

 a conehead grasshopper (Neocorwccphalus en- 

 siger), another member of the katydid family. 

 A, B, right and left front wings, showing the 

 scraper (s) on the right wing and the file vein 

 (fv) on the left. C, under surface of file vein, 

 showing the file (f). D, front leg, showing the 

 slits (e) opening into pockets containing the 

 " ears." (See fig. 35, A) 



