IN CERTAIN LEPIDOPTERA. 271 



In those abnormal cases in which the valves arc partly or wholly aborted, e. g. 

 Diphilus, Polydorus, Hector, the thatch of long hair that occasionally projects from the 

 dorsal arch of the eighth segment, and thus fills up the triangular space left by the 

 receding dorsal edges of the valves, is particularly abundant. 



The extremity of the valve shows, in almost all cases, some indication of a projection 

 of the outline into a point. Usually this part is as soft and flexible as any other ; but 

 in some instances, c. g. Scmperi, Ucalegon, there seems, in its definite form and darker 

 hue, an approach to that condition which occurs in other families of the Rhopalocera, 

 in which the valve and the harpe become one organ *. 



Mr. Wallace, in his very valuable Memoir " On Variation, &c, in the Papilionidae of 

 the Malayan Region " f, is inclined to rest on the peculiarities of the valves of Ornitho- 

 ptera for generic diagnosis. Having rejected certain points that have been relied on, he 

 says, " There remain, therefore, only the characters of the perfect insect, the most 

 important of which are the anal valves in the male. These are very large, ovate or 

 rounded, coriaceous, and not hairy, and are furnished with projecting points or spines 

 (sometimes very conspicuous) which serve to attach the male more firmly to the female 

 in copula. In several species, I have observed, these points or hooks were buried in the 

 protruded anal gland of the female, and thus effectually prevented the great weight of 

 the insects causing them to separate upon suddenly taking flight " 1. 



2. The Ilarpcs. 

 The interior surface of each valve, which, as I have said, is hollow, is the seat of a 

 peculiar organ, which appears to take a very prominent part in the prehensile function. 

 The floor proper of the valve-cavity is a thin membrane of slight tenacity, more or less 

 of a dark brown hue, and of a dull unreflecting surface. Within the hollow lies a plate 

 of what I presume to be pure chitine §, usually as transparent as glass, but tinged with 

 a yellow-brown hue, thickening at various parts, especially at its margins and irregular 



* Dr. P. B. White's memoir affords abundant examples of this combined condition. The transition seems to be 

 made in the family (or subfamily) Pieridoe. (See the supplementary note to this Memoir.) 



t Trans. Linn. Soc. xxv. p. 35, 1804. 



% But the valves in Orniilioptera Arruana and Amphrysus are densely fringed with hair-scales : Papilio Semp ri 

 has as distinct a finger-point to the valve as 0. Amphrysus : while the broad rounded outline is seen in the valves of 

 P. Zalmoans, Axion, and Broinius. This projecting finger-point, moreover, while well marked in 0. Amphrysus and 

 Bhadamanthus, becomes feeble in Arruana and Haliphron, evanescent in Remus, and is absolutely wanting in 

 Brookeana, where the valve is surrounded by a fringe of unusual density. But generic lines arc not mathematical 

 lines: and the features mentioned by Mr. Wallace are certainly characteristic, and, with the prevailing form of the. 

 harpe, go far to establish Orniiliopti ra as a good genus. 



Mr. Wallace's observation about the function of the points is most interesting ; would that we bad more of such ! 

 but, if I may venture to correct the dictum of so great an authority, I would suggest that, most probably, it was 

 not the flexible finger-point of the valve that had seized the protruded vulva of the female, since it has no resistent 

 power, but the harpe, well toothed, and of almost metallic hardness, that was concealed just beneath the valve-tip. 

 Yet, in some cases, as in P. Vcaler/on, I am not sure that the valve-point may not have a harpe-power — as I presume 

 that it has in some Pieridffi, as G'aZUdryas. 



§ The various degrees of flexibility found in the integuments of insects i.- believed to depend mi the extent to 

 which they are permeated by this substance, " a peculiar azotic matter insoluble in caustic potass " (Siebold, 'Anat. 

 Invertebr.' Loud. 1854, p. 401). 



