Chap. X. 



COLEOPTERA. 





9 



ribs are scraped by the posterior margins of the elytra, a 

 small portion of which projects beyond the general out- 

 line. In many Crioceridse, and in Chjthra ^-punctata 



Fig. 21. Necrophorus (from Landois). r. The two rasps. 



the rasp highly magnified. 



Left-hand figure, part of 



(one of the Chrysoinelidoe), and in some Tenebrionidae, 

 &c., 70 the rasp is seated on the dorsal apex of the abdo- 

 men, on the pygidium or pro-pygidium, and is scraped 

 as above by the elytra. In Heterocerus, which belongs 

 to another family, the rasps are placed on the sides of 

 the first abdominal segment, and are scraped by ridges 

 on the femora. 71 In certain Curculionidae and Cara- 

 bidae, 7 ^ the parts are completely reversed in position, 



70 I am greatly indebted to Mr. G. E. Crotch for having sent me 

 numerous prepared specimens of various beetles belonging to these three 

 families and others, as well as for valuable information of all kinds. He 

 believes that the power of stridulation in the Clythra has not been pre- 

 viously observed. I am also much indebted to Mr. E. W. Janson, for 

 information and specimens. I may add that my son, Mr. F. Darwin, 

 finds that Dermestes murium stridulates, but he searched in vain for the 

 apparatus. Scolytus has lately been described by Dr. Chapman as a 

 stridulator, in the 'Entomologist's Monthly Magazine,' vol. vi. p. 130. 



71 Schiodte, translated in ' Annals and Mag. of Nat. Hist.' vol. xx. 

 1867, p. 37. 



72 Westring has described (Kroyer, ' Naturhist. Tidskrift,' B. ii. 184S- 

 49, p. 334) the stridulating organs in these two, as well as in other 

 families. In the Carabidse I have examined EldpTirus uliginosus and 

 Blethisa multipunctata, sent to me by Mr. Crotch. In Blethisa the 

 transverse ridges on the farrowed border of the abdominal segment do 

 not come into play, as far as I could judge, in scraping the rasps on the 

 elytra. 



