154 The Bev. Lan s down Guildikg on t/ie Crépit aculum 



projection of the hemelytron which lies above it ; and it is by 

 rubbino- the one over the other that the loud or shrill sound of 

 most orthopterous insects is produced. 



One species, Locnsta eanwll/fol/a, whose call (resembling the 

 words shock — shock slowly and loudly repeated) may be heard 

 in the stillness of the night at the distance of a ?tii/e, has often 

 astonished the inhabitant of Europe on his arrival in the tropical 

 regions. It is hardly possible to contemplate a more extraor- 

 dinary scene than one of our valleys by the light of the moon, 

 decorated with the shining foliage of waving palms, and lighted 

 up by thousands of luminous Coleoptera, Avliich tlit in every 

 direction before our eyes ; while the grasshoppers, in company 

 with the Hylce and Tettigoni^e, perform their deafening concert. 

 In this most interesting species the wing-cases are admirably 

 adapted to increase the sound, being deeply concave in the 

 male, even the wings are closely pressed by the arched pteri- 

 gostia against the walls of the hemelytra, leaving a considerable 

 space vacant above the abdomen. 



The other organ to which I wish to call the attention of 

 entomologists, (and which was first noticed, I believe, by De 

 Ceer,) is situated on the anterior tibia' of both sexes in such of 

 the orthopterous insects as possess the crepitaculum or tym- 

 panum at the base of the wing-cases. In the Fabrician Locust œ 

 it consists of two approximate suboval open foramina, gibbous 

 at the sides : in his Achetœ, of two opposite oval flattened 

 openings, closed by a delicate membrane. In the true Grylli, 

 whose organ of sound (noticed by Kirby in his Introduction to 

 Entomology, vol. ii.) is very different in its structure and posi- 

 tion, these openings are wanting. 



I have no means in this distant country of examining the genus 

 Pneumora of Thunberg, the species of which are remarkable for 



the 



