SOUND RECEPTION 81 



formige Korperchen), the elevated process (zapfenformige Korper- 

 chen), and the pyriform vesicle (birnformiges Korperchen). These 

 bodies are merely complex thickened areas of the drum. A small 

 branch of the nerve goes to the folded body, where it innervates a few 

 hairs and other sensilla. The main portion of the nerve, before branch- 

 ing to each of the four points of attachment, swells. This swelling has, 



Fig. 56. Schematic dorsal stereogram of noctuid tympanic organ and 

 related structures. B, Biigel; C, conjunctiva or accessory tympanic 

 membrane; CTC, countertympanic cavity with external orifice 

 indicated by arrow; CTM, countertympanic membrane; E, epaulette 

 or nodular sclerite ; EL, electrode site ; H, hood ; L, ligament ; M^, muscle 

 originating on antero-median portion of metascutum and inserting on 

 metapostnotum anterior to CTM; Ma, muscle originating dorsally 

 on metascutum and inserting on epimeral band; MP, mesophragma; 

 MS, metascutum; Pi, pocket I of tympanic frame; PTG, pterothoracic 

 ganglion; S, sensillum; Si, metathoracic spiracle; Sg, first abdominal 

 spiracle ; SP, scutal phragma ; TAS, tympanic air sac lined with tracheal 

 epithelium; TM, tympanic membrane; TN, tympanic nerve; TR, 

 tympanic recess. (Courtesy of Roeder and Treat.) 



