340 STATES OF INSECTS. 



cimens, probably males, of the remarkable African ge- 

 nus Pneumora before alluded to % there are thirteen lit- 

 tle elevated ridges, placed rather obliquely in an oblique 

 series; and gradually", though slightly, diminishing in 

 size towards the belly : on their upper side they are flat, 

 forming nearly a horizontal ledge, but on the lower they 

 slope to the abdomen. The posterior thigh in its natu- 

 ral position covers the three first of them, and, if moved 

 downwards, would strike them all b . I conjecture, there- 

 fore, that these are the animal's instruments of sound, 

 imitating the harp or violin rather than the drum ; and 

 that the thigh acts the part of the hand or bow. The 

 abdomen of these insects being blown out like a bladder, 

 and almost empty c , must emit a considerable sound when 

 the thigh of the animal passes briskly over these ridges ; 

 and their different length would produce a modulation 

 in the sound. When struck with a pin, they emit a gra- 

 ting noise. 



In Sta-phylinus splende?is, the penultimate ventral seg- 

 ment is very deeply cleft, and the antepenultimate emar- 

 ginate in one sex, and intire in the other. In S. lamina- 

 tus, an allied species, the penultimate segment is cleft, 

 less deeply, however; but the antepenultimate is very 

 short and intire; while the fourth is extremely long, and 

 rounded at the margin, appearing as if it was only an 

 elevated part of the last-mentioned segment ; for which 

 it was mistaken by Gravenhorst d , while it is of the usual 

 form in the other sex. 



a See above, Vol. II. 395. 



b Plate XXIX. Fig. 13. Stoll. Spectres, &c. t. xxv.f. 99. 



c Sparrman". Voyage, i. 312 — . 



d Coleopt. Micropt. 1G. 



