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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



each side of the median suture. The lateral convexities (fig. 27, c) 

 bear at least faint traces of granules from which bristles arise. There 

 also occur a few bristles near the apex of the declivity. 



Stridulating accessories. — In both sexes the left elytron bears on the 

 declivity a well developed lobe which lies under the right elytron 



Prescutum 



Fig. 29. — Gnathotrichiis retusus Lee. : A, articulation of the elytra, ventral as- 

 pect; B, stridulating apparatus on the apex of the elytra, ventral aspect. 



Cal, callus; Co, costal ridge; Sco, subcostal vein; Te, tegula; a, costal head; b, subcostal head, 

 o.ri, 0.1:2, axs, axi, the axillaries; c, lateral arm of prephragma Hopk., or pleural hook of 

 scutum; d, prealar process; e, stridulating rasp; /, stridulating scraper. 



when the elytra are kept in the closed position. This lobe, the stridu- 

 latory scraper (fig. 27 d, fig. 29 f) is finely transversely sulcate on 

 the dorsal side. The corresponding area on the right elytron (fig. 29, c) 

 is also rasplike but only on a narrow strip. If these two parts are 

 grated against each other, it is most probable that they will produce 

 a chirping sound. Up to date this sound has not been heard by the 



