16 MR. A. R. WALLACE ON THE PAPILIONID^ 



In the Poli/dortf^-gTomp two species, P. Antiphns and P. Diphilus, inhabiting India 

 and the Indian region, are tailed, while the two ^hich take their place in the Moluccas, 

 New Guinea, and Australia, P. Pohjdorns and P. Leodamas, are destitute of tail, the 

 species furthest east having lost this ornament the most completely. 



Western species, tailed. Eastern species (closely allied), less tailed. 



Papilio Pammon (India) tailed. P. Thesus (islands) .... very short tail. 



P. Agamemnon, var. (India) . . . tailed. P. Agamemnon, var. (islands) not tailed. 



P. Antiphus (India, Java) .... tailed. P. Polydorus (Moluccas) , not tailed. 



P. Diphilus (India, Java) .... tailed. P. Leodamas (New Guinea) . not tailed. 



The most conspicuous instance of local modification of form, however, is exhibited in 

 the island of Celebes, wliich in this respect, as in some others, stands alone and isolated 

 in the whole archipelago. Almost every species of Papilio inhabiting Celebes has the 

 wings of a peculiar shape, which distinguishes them at a glance from the allied species of 

 every other island. This peculiarity consists, first, in the upper wings being generally 

 more elongate and falcate ; and secondly, in the costa or anterior margin being much 

 more curved, and in most iustances exhibiting near the base an abrupt bend or elbow, 

 which in some species is very conspicuous. This peculiarity is visible, not only when 

 the Celcbesian species are compared with their small-sized allies of Java and Borneo, but 

 also, and iu an almost equal degree, when the large forms of Amboyna and the Moluccas 

 are the objects of comparison, showing that this is quite a distinct phenomena from the 

 diff'erence of size which has just been pointed out. 



' In the following Table I have arranged the chief PapiKos of Celebes in the order in 

 Avhich they exhibit this characteristic form most prominently. (See Plate VIII.) 



It thus appears that every species of Papilio exhibits this peculiar form in a greater or 

 less degree, except one, P. Polyphonies, Bd., allied to P. Diphilus of India and P. Polydorus 

 of the Moluccas. This fact I shall recur to again, as I think it helps us to imderstand 

 something of the causes that may have brought about the phenomenon we are considering. 

 Neither do the genera Ornithoptera and Leptocircus exhibit any traces of this peculiar 

 form. In several other families of Butterflies this characteristic form reappears in a few 

 species. In the Picridte the following species exhibit it distinctly : — 



