738 Mr. Gilbert J. Arrow on 



Ochod^us it is liiglily specialized. The very remarkable 

 complementary structure in this isolated genus has no 

 nearer homologue than the spiny stridulating bosses of 

 the Passalidffi, which, as in the former case, occupy the 

 ante-penultimate dorsal segment. Less localized but 

 similar areas occur upon the back in certain Geotrupidae 

 not provided with coxal organs. With the exception of 

 Fhileurus, in which I believe the method used to be 

 similar to that of the Geotrupidse just mentioned, and 

 Ligyrus, all stridulating Djaiastida^ bear vocal ridges upon 

 the propygidium ; those of the Rutelida3 are near the ends 

 of the femora and those of the Cetoniidae beneath the 

 abdomen. In the only known stridulating Melolonthid 

 genus, Serica, the ridged plate is within the presternum. 



APPENDIX. 



Systematic notes and dcsci^i-ptions of Lamellicornia referred 

 to in the foregoing iiaper. 



Certain of the beetles just dealt with being hitherto 

 unknown or little studied, it has been necessary to use 

 new names and even to form fresh groups, and I have 

 therefore to supplement what has been said by more 

 comprehensive technical descriptions of these. It will 

 be convenient also to consider here the bearing of the 

 facts already dealt with upon the inter-relationships of 

 the groups of Lamellicorn beetles, concerning which 

 stridulating organs seem to me to afford evidence of some 

 importance. 



The classification of the species of ^gidium, one of 

 the genera in which I have found stridulating organs, is 

 in a state of some disorder. I have pointed out in a 

 former paper that the Central American insects ascribed 

 by Bates to ^gidium colom'bianiim do not belong to that 

 form, and I have since found that the name j^. asperatttm 

 was given by De Borre the year previously to what is 

 evidently a not well developed specimen of the same 

 species from Ecuador. The type of ^. Beichei of De 

 Borre is probably only a very small individual of the 

 same species, — at least no differential characters are 

 described. 



