IN" CEETAIX LEPIDOPTEEA. 335 



APPENDIX. 



Supplementary Note to Ornithoptera Remus. 



Since this Memoir was completed, and presented, many examples of this magnificent 

 butterfly have been sent to me from Celebes, and also of O. Haliphron ; and I have 

 examined more than a dozen males of each. The following notes embody my latest 

 researches on the abdominal organs. They are illustrated by figs. 15-19 of Plate 

 XXVII. [N.B. The small letters indicate the same organ or part in each figure.] 



Uncus (a). When the beautiful patch of velvet-black hair-scales that adorns the 

 dorsum of the eighth segment of O. Remus is carefully removed by abrasion, so as to expose 

 the chitinous skin, we see that this is dully shining up to the accurately defined trans- 

 verse line where the velvet ended. Thence it becomes brilliantly polished, and begins 

 to project into a triangular area, of which the lateral edges are thickened, while the 

 median portion, also thickened, forms the out- and downcurved uncus. Its curvature 

 is not quite uniform : sometimes it is the arc of a circle, sometimes the arc of an ovoid ; 

 sometimes it is bent abruptly and perpendicularly downward from its middle. 



Scaphium (b-i). From a level slightly below the expanding rami of the uncus, appa- 

 rently in fixed immovable connection with it, spring a pair of slender rods, of similar 

 shining chitine, each of which (b) is dilated near its base into a wide lamina exteriorly, 

 which lamina? become the firm fleshy tissue of the cheeks (c). These together assume 

 the form of one fourth of a globe, cleft by a deep vertical sulcus, which has a continuous 

 floor (d). Each cheek has its outer ventricose side obliquely cut away behind : its 

 surface is distinctly granulate, the granules elevated, more and more towards the point 

 and back, into the characteristic stiff, glittering bristles (e). 



A simple device may assist the comprehension of this form. If the thick rind of half 

 an orange be removed bodily and set on its edge, if then about half of this be cut away 

 slantingly behind, and then what remains lie excised into a deep narrow groove mesi- 

 ally, we shall get the scaphium-cheeks of O. Remus. 



Erom just below the groove descends vertically a long and narrow pentagonal piece 



J (/) of what simulates polished ivory. It is not continuous with the part from which it 



i seems to descend ; for, by peering with a lens under I lie edges of the cheeks, we see the 



summit of the pentagon to lie abruptly bent backwards, so as to reach connection with 



the under surface of the sulcus-floor, far back in the mid-roof of the arch. 



Behind this narrow shining pentagon is the keel {g) ; a large plate of whitish tissue, 

 I very thin in the middle, which seems attached to the concealed side of the pentagon, but 

 on the abdominal side thickening into broad irregular lobes (/i), apparently of a different 

 t character from the thin central parts. The depth of this organ, and even its shape, 

 differs considerably in different individuals. Possibly it is capable of alteration in form, 

 and may be composed of something analogous to erectile tissue. Indeed, I have fancied 

 that the varying direction of this curious member — sometimes more, sometimes less 

 pendent — may itself indicate a sort of erection. May it be that it is a titillant, excitant, 



