270 ME. P. II. GOSSE OX THE CLASPLNG-OEGANS 



follow a pretty uniform ratio, which may be set down as about 7 diain., with which ratio 

 the figures of the other organs may be compared. 



A General Description of the Organs. 



The organs with which I propose to deal, as limited to the male sex of Butterflies 

 belonging to the two genera Ornithoptera and Papilio, are the following: — 1. The 

 Valves; 2. the Harpes ; 3. the Uncus ; i. theScaphium; 5. the Penis. 



1. The redoes. 



To the overlapping edges of the eighth abdominal segment, from the indefinite points 

 where the projecting angular portion produced by the rami of the uncus merge into the 

 vertical, to two prominent rounded pieces Avithin the ventral margin, there are united, 

 by free-working joints, two broad plates, well known under the name of valves *. Every 

 collector is familiar with these organs ; for he has recourse to them to determine, at a 

 glance, the sex of his specimens, since, in the grand genus Pap'dio, they arc peculiar to 

 the male. 



Their outline is usually more or less trigonal, often becoming semiovate, or even sub- 

 circular. To be more precise, the prevailing shape is that of an oval, or rounded rhom- 

 boid, cut off obliquely, so that as we look on the inside of the right valve the tip points 

 to the left — that is, toward the dorsal side. 



They are clothed on the exterior with scales like those of the body. Their direction 

 follows the general plane of the sides of the abdomen ; they are convex externally, con- 

 cave internally. Their free edges are commonly furnished with a fringe of modified 

 scales, taking the form of thick hairs, which are parallel, close-set, often dense, and often 

 long ; thus these practically enlarge the area of the valves, and help to exclude, more 

 effectually, extraneous matters from the genital cavity when the valves are closed. 

 Sometimes dense brushes of long hair, of quite different structure, arise from within the 

 interior of the valve, which spreading, conceal the margin, and greatly modify the 

 apparent outline ; e. g. JPoliccnes, Ucaleyon. 



The friuged edges come into contact when the valves are at rest, inclosing a spacious 

 chamber, the anal, or genital, cavity. The edge is occasionally turned over, narrowly, 

 within ; e. g. Ornithoptera HaUphron ; and still more commonly the interior surface 

 continues fiat and level for some distance within the margin, then abruptly drops to the 

 central cavity; e. g. Agamemnon, Hesperus, Lycidas, Anchisiade-% Eurylcon. Occa- 

 sionally a sort of wall, of distinct form and surface, borders the edge, and overhangs the 

 interior ; e. g. Zalmoxis. The floor of the interior, whether fiat or hollow, is often 

 studded with short scattered hairs, each springing from a dimple, or crowning a minute 

 round hillock, where it is not occupied by the harpe : but sometimes this surface is 

 cloth-like; e. g. Erithonius, Lycidas. 



* A better name would be tegumina, covers; but this word has been chosen by Dr. B. White for a very different 

 neighbouring organ. Colei (icoXebs, a sheath or scabbard) might be used ; or, to avoid ambiguity with the genus 

 Culms of the botanists, it might be spelled in its Ionic form, Kovkebs. But I adopt the appellation already in 

 familiar use. 



