542 REVISION OF THE GENERA COLPOCHILA, ETC. 



could not be Melolontha pruinosa, Dalm., (as more fully described 

 by Dr. Burmeister). My conclusion therefore is that if the 

 specimen credited with being the type of Cotidia australis is 

 congeneric with Sericesthis geminata, Boisd., that specimen cannot 

 have been correctly identified as the type, and that the only 

 possible course is to erase Cotidia australis altogether from the 

 Catalogue as absolutely incapable of identification. 



The sexual distinctions of Sericesthis are very uncertain and I 

 do not know even one that can be called genuinely characteristic 

 of the genus, — indeed to determine the sex of a given specimen 

 (without dissection) it is frequently necessary to fall back on the 

 slight clue afforded by the convexity or otherwise of the outline 

 of the ventral segments viewed from the side. M. Lacordaii'e 

 states that the males have the joints of the antennal flabellum 

 elongated and the apical ventral segment emarginate behind, but 

 I do not find these characters reliable. In S. pruinosa, Dalm., 

 the apical ventral segment of both sexes is emarginate and (beyond 

 the convexity or otherwise of the hind body) I can find no sexual 

 difference except in the antennal flabellum, even the length and 

 robustness of the tarsi scarcely showing any sexual difierences. In 

 *S'. dispar, Blackb., both M. Lacordaire's distinctions hold good and 

 in addition the male is black and the female red. In ])Ianiceps, 

 Blackb., the male has the joints of the antennal flabellum quite 

 short (shorter than in the female of -S*. pruinosa, Dalm.) and the 

 apical ventral segment emarginate behind, while the female (if I 

 am right in its identification) scarcely difiers except in being of a 

 lighter colour, in having the apical ventral segment difierent, and 

 in being less narrowed and more ovate. I cannot doubt the 

 specimens of ^S*. planiceps which I regard as males being really of 

 that sex in spite of the shortne.ss of the joints of their antennal 

 flabellum, — their narrow elongate form, hind body not convex 

 longitudinally, very strongly tumid pygidium, strongly emarginate 

 apical ventral segment and extremely long tarsi being in combina- 

 tion I think quite conclusive. 



The species of Sericesthis present no less difficulty than the 

 generic name, — so much difiiculty in fact that it will be necessary. 



