18 Mr. J. O. Westwood on the Chalcidida. 



for example we will suppose to be the trophi, running, with but 

 little variation in their formation, through a certain series of groups or 

 genera of various external appearance, each of which groups, never- 

 theless, possesses peculiar habits, we ought to consider the characters 

 drawn from such organs as characteristic of the whole of that series, 

 be it either a family or a subfamily. Now, wherever the trophi are 

 found to be such slightly varying organs, we must of necessity resort to 

 variations exhibited by other organs, such as the legs, antennse, wings, 

 or other external parts, and these will therefore be found to supply the 

 essentia! characters of the genera. Such genera, although " they have 

 no better claim to distinction" than these external characters, here necessa- 

 rily become generic, (which Mr. Curtis has nevertheless recently thought 

 proper to designate " mere outline, or suchlike secondary charac- 

 ters,") * rest upon so " solid a basis" that it will require the exertion of 

 more than a single Entomologist to shake them from their foundation, 

 however that Entomologist may, perhaps, at the present time be in- 

 clined to imagine that the number of genera may be diminished vrith 

 impunity, unmindful that by such a proceeding the benefit to, and the 

 advancement of, science, that stimmum bonum, at least as it ought to 

 be, of every Entomologist, must of necessity suffer in the attempt. That 

 the opinion which I, as an advocate for external characters and organi- 

 zation, have ventured to express above, is not contrary to the principles 

 upon which modern genera are established, is evident ; and I feel con- 

 vinced that no one can on the one hand examine Mr. Curtis's dissections, 

 for example, of Colax, Perilampus, and the insect which he has named 

 Cleonymus maculipennis, or those of several genera of Tenthredinidae 

 figured by the same author ; and, on the other hand, peruse the fol- 

 lowing remark of Mr. Stephens, " The trophi of Platyderus and the 

 five following genera are so extremely similar, that the species have 

 till lately been considered as constituting one genus only, but there 

 are several striking external characters by which they may be advan- 

 tageously separated,"! and then boldly assert, that in such and many 

 similar cases the trophi are the organs first to be investigated, and 

 principally to be relied upon as affording generic characters, and that the 



• British Entomology, No. 207. f Illustrations, Mandib. Vol, I. p. 101. 



