30 Rev. F. D, Morice on male terminal segments and 



dorsal plate. Springing from the apex of this arch appear 

 nearly always two large symmetrical lobes or "wings." 

 They are perfectly colourless and membranous at the 

 extreme apex, still membranous, but more or less in- 

 fuscated, punctured, and pilose on the disc, evidently 

 chitinized at the base and along the inner margin, and 

 at least somewhat thickened and darkened on the exterior 

 margin. Each of them consequently has the appearance 

 of a frail membranous sheet stretched on a more solid 

 framework, which supports it much as the costa and 

 ne'rvures support a wing. 



The form, colour, and pilosity of these lobes differ 

 specifically to such an extent, that many species can be 

 distinguished at a glance by these characters alone. Not 

 only the actual outlines, but even the minute veinings, 

 cloudings, etc. of the membrane seem to be extremely 

 constant. The only difficulty in examining them is that 

 they are apt to curl over somewhat at the apices laterally, 

 but even this curling sometimes contributes to their specific 

 " facies." I have frequently dissected many specimens of 

 one species from widely-different localities, and have 

 nearly always found their seventh segments exactly similar, 

 and quite unlike that of any other species. The cases in 

 which two different species have this plate deceptively 

 similar, are extremely rare ; and curiously enough, where 

 this docs happen, the insects themselves are generally very 

 unlike each other in external characters. 



Tliese segments have, for examination, at least one great 

 advantage over the armatures proper. Their outlines are 

 real margins and not mere variable horizons of solid figures, 

 hence their ajjpearance is much less affected by slight 

 differences of jDosition. Also being much less complicated 

 objects, and less troublesome to focus under the microscope 

 (being flatter), they produce an impression which is more 

 (juickly grasped and more readily remembered. 



It is perfectly easy, with a little practice, so to prepare 

 either fresh or relaxed specimens as to display this segment 

 sufficiently for all practical purposes ; or it can be actually 

 removed and mounted separately without any noticeable 

 disfiguring of the specimen, but in that case the ligaments 

 connecting it with the dorsal plate must be severed 

 cautiously first. In nearly all cases it forms a most 

 beautiful microscopic object, whether it be mounted dry 

 or in balsam. 



