452 Mr. Charles J, Gahan on Stridnlating Organs. 



segment of the abdomen. These ridges have been referred 

 to by different authors, as a stridnlating apparatus, but I 

 think they can only be doubtfully regarded as such. I am 

 not aware that these beetles have ever been heard to 

 stridulate. 



As these pages were passing through the press, Mr. 

 Distant called my attention to some remarks in reference 

 to stridulation which appear in a work entitled " On the 

 Indian Hills," by Edwin Lester Arnold (vol. ii. p. olo). 

 Mr. Arnold, struck by the loud noise made by a large 

 Longicorn beetle, Batoccra rubus, was desirous to find out 

 how the sound was produced, so he "took him home and 

 investigated " ; and with what result, he goes on to tell 

 us: "He squeaked most strangely all the time, moving 

 his head backward and forwards and waving his antenna3. 

 This gave me a chie, and I dipped a small feather in oil 

 and passed it lightly round the junction of the head and 

 thorax, and in a moment all sounds ceased though the 

 insect still continued his movements, and it was plain the 

 sound had been caused by friction of his head and neck." 



Now as it is well known that Batoccra squeaks like 

 other Longicorns by rubbing the protliorax over the 

 stridnlating area on the mesonotum, which is very large 

 and conspicuous in this genus, I am at a loss to explain 

 why all sounds ceased when oil was passed between the 

 head and protliorax. The inference drawn by Mr. Arnold 

 was of course wrong, but it serves to show how easily 

 mistakes of the kind may be made, even by painstaking 

 investigators. 



EXPLAXATION OF PlATE VIL 



ISee explanation faring the Plate.] 



October 22, 1900. 



