98 THE entomologist's RECORD. 



and Salvin mention it but give no details other than* " There are two 

 rods attached to the upper edge of the ventral portion of the terminal 

 segment of the abdomen." 



To sum up : This organ is peculiar to the <? and displays distinct 

 characteristics in all the different species I have examined. 



My colleague M. JuUien discovered an organ in certain Satt/ridae. 

 This organ, called by Fruhstorfer " Jullienische Organ," is composed 

 of thick, chitinous, very darkly coloured rods with dentated or pointed 

 extremities ; these rods are inserted in the last abdominal tergite (not 

 the sternite); they are found in Satyriis alcyone, S. Iierviume, S. ^yriaca, 

 and S. seuiele, and in Epinejihele jiirtina, in which latter there is one 

 instead of three or more rods on either side ; but this one rod is really 

 formed by the soldering together of several into one multidentated rod. 

 In S. hermione and S. alcijorie the insertion is made in a sort of wing 

 detached from the lateral parts of the tergite, whereas in E.jitrtina it 

 is made on the slight prolongation of the somewhat flattened exterior 

 angle of this sternite. 



The analogy is evident if not close ; it is true that the points of 

 insertion and the dimensions of the rods are very different in Satyrus 

 and* in Aiiemnia. There is, however, analogy enough to cause us to 

 suspect that their functions are similar. 



Dampf thinks that Jullien's organs are scent organs, but Jullien 

 himself believes them to be of a tactile order, and the latter hypothesis 

 seems more in keeping with their constitution ; it is hard to see how 

 these thick rods can disperse a volatile substance. 



A third solution of the problem suggests itself to me. I have read 

 a remark by Fritz Miiller incorporated in Dr. G. B. Longstaff''s work.f 

 " Just as the Ageronia, four species of which I had an opportunity of 

 observing in some numbers during the past summer, only make the 

 remarkable crackling sound on the wing and during the courtship, so 

 also, in all probability, butterflies equipped with brands, tufts, etc., 

 only distribute their scent under the same circumstances." May we 

 not deduce that this crackling sound is caused by the friction of the 

 spiculse against other parts of the genitalia, and that the Jullien organ 

 has the same function, the action being modified by their situation ; it 

 would seem almost as though the motionless organ of Acieronia were 

 rubbed by the mobile valves, whereas the mobile spiculte of the Jullien 

 organ in Satyrus rub against the valves or uncus ; the way in which 

 the Jullien organ is inserted leads us to suppose that it can be moved 

 at will. I submit my hypothesis to the numerous and clever English 

 observers, and to the Swiss field-workers ; they will perhaps tell me 

 if E.jitrtina and S. alcyone perform on the castanets as Ayeronia does 

 in order to charm its lady mate. 



Explanation of Plate II. 



Fig. 1. Ageronia febriia, <?, genitalia and Godman-and-Salvin organ. 



Fig. 2. Ageronia arete, <f , 8th abdominal segment. 



Fig. 3. Ageronia obidana, S , 7ib and 8th abdominal segments. 



Fig. 4. Ageronia jritilla, <? , 8th abdominal segment. 



Fig. 5. Ageronia saurites, i , 8th abdominal segment. 



Fig. 6. Ageronia sellasia, <? , 8th abdominal segment. 



* " Biologia Centrali-Americana." Insecta Lepidoptera Rhopalocera , by F. 

 D. Godman and D. Salvin. Vol. i., p. 268. 



f Butterfly -hunting in many Lauds. George B. Longstaff. p. 616. 



