450 Mr. Charles J. Gaban on 



though Wollaston previously professed to have discovered 

 it in a rather large granulated or shagreened area of trian- 

 gular shape placed close to the apex on the underside of 

 each elytron. The true stridulating area, as Landois has 

 correctly observed, lies close to the suture, and is povered 

 with very regular and parallel transverse ridges, giving it 

 an appearance quite distinct from the reticulated or granu- 

 lated surface on the outer part of the triangular area. The 

 male only of Cryptorliynchus la]jathi possesses this elytral 

 file, the female being without stridulating organs of any 

 kitid. The same sexual difference was apparently met 

 with in all the species examined by Landois, who has too 

 hastily generalised in stating that stridulating organs are 

 present in the male sex only of Curcidionid.v. In Plinthus, 

 AcaUes, Mononyclius and other genera which I have in- 

 vestigated, stridulating files were found to be present on 

 the elytra in both sexes ; while in many forms the stridu- 

 lating files are present in both sexes, but occupy a different 

 position in each sex, being placed on the elytra in the 

 males and on the pygidium in the females. The latter 

 condition occurs in Cryiitorhynehits lirimis, Boh., C. Icmni- 

 scatus, Boh., and other (probably several) species of Cryjjto- 

 rhynchus, in the species of the genus Camptorhimts, in 

 Gasteroccrcvs irropugnator, Sch., Edatorhina icallacci, Lac, 

 and in other genera. The form and position of the pygidial 

 files in the female of C. lirinus, figs. 12 and 12/', and of 

 Camptorliinus sp., figs. 13 and 13?>, are shown on PI. VII; in 

 both cases, as in others of the same kind, each of the two 

 files lies along the inner side of a conspicuous triangular 

 area, the outer jjart of which is usually covered with a fine 

 silky pubescence. A strongly-marked ridge wliicli crosses 

 the underside of the elytron obliquely a little in front of 

 the apex acts as the scraper, the inner part of the ridge 

 (that next the suture) being almost directly transverse and 

 somewhat sharper than the rest (see PI. VII, figs. 12rt and 

 loa). A similar ridge present in the males of the stridu- 

 lating species, stops short as a rule before reaching the 

 suture, allowing the elytral file to extend forwards a short 

 way in front of it (see fig. 5a). This condition occurs also 

 in those females in Avhich the files are situated on the 

 elytra. 



The scraping of the elytral files is usually effected by 

 means of a series of little granules or tubercles placed at 

 intervals along the pygidium in the females, and along the 



