Stridulating Organs in Coleo^itera. 435 



single stridulating file on the crown of the head in tlie 

 genus Goniolanguria, and that there were two such files in 

 the genus Tcrciilanguria. Dr. D. Sharp has since detected 

 the presence of a stridulating area in the same position in 

 the genus Ips and allied forms of the family Nitidulidie, 

 and Mr. Gorham has discovered it in two species of 

 Endomychid;v — Encymon ruficollis, Kirsch, and PhcV- 

 omychtis rufijKnnis, Motsch., as well as in some additional 

 genera and species of Languriinx. 



In the Endo7nycliidcV^ stridulating organs are much more 

 generally present than Mr. Gorham seems to have sus- 

 pected, and it is owing, perhaps, to the somewhat excep- 

 tional character of the striated area in Encymon ruficoUis, 

 that his observations in reference to this s]3ecies are not 

 altogether accurate, " The true characters are," he says, 

 " sexual and very interesting. The male in this species 

 has the head furnished with a stridulating file on the 

 crown formed of fine transverse striae, the front edge of the 

 thorax in this sex having a small fossa corresponding to 

 an internal projection for the purpose of rasping the file. 

 This apparatus does not exist in either of the allied 

 species ; although the fossa is feebly present in some 

 specimens, there are no corresponding striae." 



I have, as I believe, correctly determined the sexes of 

 E. ruficoUis, and I find the stridulating area present and 

 having the same appearance in both sexes. It consists of 

 two portions differing in the character of the striation. 

 The more coarsely striated part lies in front, and is 

 generally exposed to view, while the more finely striated 

 posterior area is usually hidden under the pronotum. In 

 his examination of the species, Mr. Gorham seems to have 

 seen only the anterior more coarsely striated area, and to 

 have overlooked the other portion, which, in position and 

 in the fineness of its strice, corresponds almost exactly with 

 the stridulating area present in all other species of the 

 genus Encymon, and in those of several other genera of 

 Endomychidse. 



Certain authors appear to set very little or no value 

 whatsoever on the stridulating organs as affording char- 

 acters to be used in the classification of Coleoptera. 

 There can be no doubt that these organs have arisen 

 independently in the same position and with an almost 

 exact identity of structure in different families of beetles, 

 so that it would bo wrong to assume from any close 

 TRANS. ENT. SOC. LOND. 1900. — PART III. (OCTOBER) 29 



