ORGANS OF SENSE. 



25 



Man, 1st Edition, Vol. i, 1871, pp. 378-385) ; and Landois dis- 

 cusses them in detail in his ' Thierstimmen ' (Freiburg, 1874). 

 Mr. Gahan has more recently published an excellent paper entitled 

 " Stridulating Organs in Coleoptera " (Trans. Ent. Soc. Lond. 

 1900, pp. 433-452), in which he divides them under four heads, 

 as follows : — 



1. Stridulating organs on the head (p. 434). 



2. Stridulating organs on the pro thorax and front legs 



(p. 441). 



3. Stridulating organs in the mesothorax and middle legs 



(p. 443). 



4. Stridulating organs in the hind legs, elytra, and abdomen 



(p. 446). 



In one form or another these organs are found in a large 

 number of families (Cigine-elid^;, Carabid^:, Dytiscid^e, Endo- 

 mychid/e, Heterocerld^;, Elaterid.e, CeRAMBYCIDjE, Chryso- 

 melidjE, Curculiontd^;, Scolytid-E, etc.), but appear to be chiefly 

 developed in the Lamellicornia, in which sub-order many of the 

 larvae have the power of stridulation, as well as the perfect insect ; 

 several of these appliances in the larvae are figured by Schiodte 

 {Naturhistorisk Tidssknft, Ser. 3, Vol. ix). Dr. Ohaus and 

 Mr. Arrow have done much to increase our knowledge of these 

 structures, and their work will be alluded to more in detail under 

 the Lamellicornia. 



The Bostrychid;e and Anobiid^: produce, in several instances, 

 tapping sounds, but some of their members appear to have a 

 stridulatory apparatus as well. On this point, Mr. Gahan writes 

 as follows: — "In the genus Anobium proper, the gula is less ex- 

 tensive than in Priobium, and has no trace of a stridulating area, 

 but in mauy of the species there is a curious series of ridges on 

 the underside of each elytron close to its outer and apical margin, 

 suggesting that the elytra may in these cases be used for purposes 

 of stridulation. These ridges are not present in Priobium and are 

 wanting also in Xestobium tessellatwn, one of the species which 

 are known to make a noise by tapping their head against the wood 

 on which they stand." 



The beetles belonging to the curious Longicorn genus PJagitli- 

 onysus, from the Hawaiian Islands, appear to have three means of 

 stridulating; firstly, by moving the edge of the prothorax over a 

 striated area on the mesosternum ; secondly, by means of a stridu- 

 lating file along the lateral edge of each elytron against which they 

 rub the hind femora ; and thirdly, by means of a series of ridges 

 which is present on each of the middle and hind coxae; these are 

 in some species very regular and parallel, and are considered by 

 Dr. Sharp, who discovered them, to be true stridulating structures 

 (v. Gahan, I. c. p. 446). 



Several beetles produce a loud humming noise ; this is partly 

 cnused by the wings, but is also due to a chitinous process in the 

 large trachea, just behind the spiracle, which is thrown into 



