444 Mr. Charles J. Gahan on 



rule of the same character throughout the whole of the 

 stridulating area, and show no appreciable difference 

 according to sex, though varying in number and the 

 degree of fineness in different species and genera. The 

 only exceptions to this rule, so far as I know at present, 

 are met with in the Madagascar sjenera Ranova, Lcuco- 

 grcqjhis and Lasioccrcis. In these the ridges are much 

 coarser in the male than in the female, and in both sexes 

 become distinctly coarser and less approximate to one 

 another in passing from the hind to the front end of the 

 stridulating area. 



Stridulating organs similar in character and position 

 to those of the Longicorns are found in the Phytophagous 

 beetles of the family Mcgalopidx. They were first noticed 

 by Lacordaire, whose observations in reference to them 

 seem to have been entirely overlooked by subsequent 

 writers. They appear to be present in both sexes throughout 

 the whole family. 



Stridulation in beetles of the family Glythridm is noted 

 by Darwin in his " Descent of Man." He attributes the 

 discovery to Crotch, and states, erroneously, that the 

 stridulating area is situated on the pygidium. The stridu- 

 lating areas — two in number — are on the mesonotum, 

 lying close alongside its lateral edges. I have found them 

 present in most of the species which I have examined, but 

 tliey appear to be altogether absent in a few genera, and 

 are wanting also in certain species of Clythra which differ 

 in other respects from the remaining species of that genus. 

 Stridulation can be easily produced in cabinet specimens 

 of some of the larger species, by forcibly moving the 

 prothorax backwards and forwards over the mesonotum. 



The most interesting, perhaps, of all the stridulating 

 organs of Coleoptera are those discovered by Schiodte in 

 the larvae of Lucanid.v, FassalidcV and GeotrwpidcV, and 

 figured and fully described by him in the " Naturhistorisk 

 Tidsskrift," Ser. 3, Vol. IX (1874). In these larvre the 

 sound-producing organs are situated entirely on the legs, 

 a series of ridges or tubercles on the coxee of the middle 

 legs constituting the rasps or files, and structures adapted 

 for the purpose on the hind-legs acting as the scrapers. 

 In the larvae of the common stasf-beetle, a ridcje aloncy the 

 anterior face of each of the hind-legs is made up of a 

 series of short transverse tubercles, and stridulation is 

 produced by drawing this ridge along the hard, serrate or 



