i8j»7.] 207 



the South African Trox peniclllatm* the structures are similarly 

 situate, though the thape of the penultimate dorsal plate is rather 

 widely different. 



These structures are beautifully developed, and have no doubt 

 escaped notice because the striate ridges are very slender, so that their 

 characteristic sculpture will not be seen unless looked for. 



As regards the structure alluded to by Leconte and Horn, I 

 believe it has no connection with the stridulatory apparatus. A much 

 more extensive and highly developed system of similarly prepared 

 surfaces exists in the Passalid(B in connection with the spiracles, and I 

 incline to the opinion that these structures will be found to be con- 

 nected with respiration. The inner faces of the elytra of many beetles 

 have a beautifully pearly or minutely polished surface at the spot 

 where they are in apposition with the chief abdominal spiracle on each 

 side of the body. The presence of this area appears in fact to be the 

 rule rather than the exception in Goleoptera. 



Cambridge : July 2lst, 1897. 



A CUEIOUS HABIT IN CERTAIN MALE PERLIBM. 

 BY C. A. BRIQGS, P.E.S. 



The Perlidce are such bad subjects for the damp box that I always 

 bring home my specimens alive in glass-topped boxes, killing and 

 setting them at leisure. It is owing to this that I noticed the curious 

 habit to which I refer. 



One day while sitting with a number of full boxes on the table 

 before me, my attention was aroused by a low but distinct tapping 

 noise, which I ultimately traced to boxes occupied by ^ GJdoroperla 

 grammatica. At first I thought it was a case of stridulation, but 

 further observation showed that the noise was entirely caused by 

 percussion, and was produced by the i^ curling upwards the last seg- 

 ment of the body and striking the bottom of the box violently with 

 the under-side of the next segment, just where there is a little hard 

 protuberance ; the caudal setae being violently agitated at the same 

 time. 



I have since watched a great number of specimens, and though I 

 have occasionally noticed the rapping while the insect was on the side 

 of the box, 1 have never noticed it while the insect was clinging, 



* The specimen examined is from the Hedjaz province of Arabia, whence the species has, 

 I believe, not been previously recorded. 



