i68 



a single aspect, or at most from two. The way to elucidate 

 a new species by illustration is to illustrate just the character or 

 characters which will best diñerentiate it from its already known 

 allies. It would be easy to cite scores of examples in the 

 Lepidoptera, and to our coleopterist and other friends similar 

 cases would occur in thousands. I will content myself with 

 two or three from the Geometridœ. In Dr. A. J. Turner's 

 recent masterly revision of the Australian Sterrhinœ = Acida- 

 liinœ,^ which as a matter of fact is entirely unillustrated, but 

 by means of which I am able to work out my material with a 

 precision for which I could never hope from the Acidaliid figures 

 in, let us say, the Biología Centrali- Americana, various species 

 [e.g. of Leptomeris) are differentiated by the male hindtibial 

 structure ; for instance, L. thysanopus Turner, n. sp., is dis- 

 tinguished from L. optivata Walk., by " posterior tibiae of male 

 more strongly dilated in basal half, with two tassels at base." 

 If an illustration is to be demanded — which is really superfluous — 

 let me implore, in the name of common sense and practical utility, 

 that it should be a figure of an enlargement of the male hindtibia, 

 and not a drawing of the wing-area, for which Turner has been 

 able to bring out no more momentous differentiation than " ab- 

 sence of blackish scales from cilia " — likely enough to be missed 

 by even the most careful artist if he were asked to draw figures 

 of the two species in question, on which posterity was to depend. 

 In my own paper on the Geometridœ of the Argentine Republic ^ 

 I described and figured a species Salpis rubens, and described but 

 did not figure a very close ally, S. carneitincta ; had I figured it, 

 I feel sure that three out of four students of the plate would not 

 have been able to name their specimens from it — which, if I may 

 be permitted to say so, seems to be the matter of supreme im- 

 portance in M. Oberthür's estimation ; but a few words of 

 description of the distinctions in the antennal ciliation have ren- 

 dered differentiation certain, and if I were called upon to furnish 

 an illustration (again "really superfluous"), I should certainly 

 give drawings of a few joints of the antenna, strongly magnified. 

 The same remarks appl}' to Craspedia deserta Warr.,' in its less 



^ Proc. Linn. Soc. N. S. Wales, xxxii., 635-98. 



2 Trans. Ent. Soc. Lond., 1910, pp. 204-345. 



3 Novit. ZooL, iv., 51. 



