A HITHERTO UNKNOWN ORGAN. 97 



A hitherto unknown organ in the Ancillary Appendages of the 

 Lepidoptera (Ageronia sps.). (M'/VA jdate.) 



By Dr. J. L. REVERDIN (Geneva). 

 (Translated by P. H. Muschamp, F.E.S.) 



Among some mounts that M. Fruhstorfer had begged me to make 

 to facilitate his studies, was one of the J genitalia of an Aijeronia, 

 and I was surprised to find in this butterfly an organ unknown to me. 

 ]\I. Fruhstorfer has since then kindly handed me the abdomens of 26 

 species of this genus, and in all I have found the same organ ; it 

 belongs exclusively to the J . 



Here is a description of this organ : It is placed in the last section 

 of the abdomen and is formed of a chitinous rod of varying length 

 and springs from the upper-posterior angle of the 8th abdominal 

 sternite. The form and curve of this rigid rod would appear to be 

 constant ; it bears at its extremity thick pointed chitinous spiculae, 

 varying in different species, and all along the rest of it fine hairs and 

 a certain number of spiculfe, which in certain species are more abundant 

 than in others. The rods are very long in certain species, shorter in 

 others ; they are rectilineal or slightly curved, generally strongly 

 concave at foot, their extremity is often clubbed, sometimes imper- 

 ceptibly ; the upper border of the sternite seems to be thickened; it is 

 both extended with the wand to its source and prolonged on its 

 proximal side to a point considerably beyond the sternite (figs. 2 and 4). 



When the genitalia are completely sheathed by the abdomen, the 

 extremity of the rods extends beyond that of the abdomen, and in dry 

 specimens these rods are easily broken off or deprived of their spicuhi?; 

 among the abdomens, which I received from M. Fruhstorfer, such 

 accidents had been rather frequent. 



Each species of the genus Agenmia possesses these organs and of a 

 form peculiar to the species. The accompanying figures show the 

 different types of rods, and it will be seen that the diagnosis of a 

 species might be established by an examination of the rods alone. I 

 must confess that I possess only one specimen each of many species, 

 but those of which I have several specimens (four specimens apiece of 

 five species, and two of several others), the form of the rods may be 

 said to be constant, any slight difference in the mounts being due to a 

 difference in their orientation. As I just observed, the spicuhe are 

 liable to be broken off', but it is always easy to ascertain their true 

 number by counting the little circles in the surface of the rods, for 

 these are the points of insertion of the detached spiculae. The 

 examples of which I have had photographs made are naturally those 

 which seemed to me to be most nearly intact. The spicuhe are 

 generally densest at the extremity of the rods, but in certain species, 

 ejj., A. satirites (fig. 5), they are dense throughout the whole length. 

 The spicuho terminate in pin points (figs. 5 and 6) or in lance-heads 

 (figs. 1,2, b, and 4); and in some of the other species, the distal border 

 of the sternite, below the spot where the rod is inserted, is furnished 

 more or less abundantly with long, heavy spiculte. 



This peculiar A;/eronia organ has not escaped observation ; Godman 



May 15th, 1915. .^<^!^^ n**''^?^ 



' jijiN] % 1S16 



