110 Mr. G. A. K. Marshall on Dicqiosematism, ivith reference 



actually on the thorax itself. When we turn to P. 

 zacynthus and its allies we find that they have no red 

 spots on the wing, but only on the thorax ; a condition 

 which is highly characteristic of Papilio, but which never 

 occurs, so far as I am aware, in any Pierine. At first sight 

 it might appear as if this furnished good evidence as to 

 Archonias having mimicked the Papilio in this respect, 

 especially as the most primitive species has no red spots 

 at all. But this view is rendered less probable by the 

 occurrence of similarly placed markings in various non- 

 mimetic species of Catastida and other closely allied 

 Pierine genera. On the other hand, Dr. Dixey advocates 

 the opposite view, namely, that the Pierine has influenced 

 the Papilio. But a consideration of the prevalence of 

 these red spots in the latter genus shows that this 

 suggestion is even less probable than the other. 



In Rothschild and Jordan's revision of the American 

 Papilios (Nov. Zool., 1906, p. 435) these insects are 

 divided into three sections. The first of these, the 

 Aristolochia Papilios, again fall into four groups. Now 

 the first three groups contain no less than 45 species every 

 one of which has thoracic spots like those of P. zacynthus 

 (which belongs to the third group), although many of the 

 species have no mimetic relations with any Pierines. In 

 the fourth group the red spots are replaced by yellow or 

 white, except in the case of polydamas and its numerous 

 races, in which the spots are red and there is in addition 

 a red spot at the base of the hind-wing. Again, basal 

 red-spots on the hind-wing are to be found in a consider- 

 able number of American Papilios belonging to Section III, 

 in which there can be no question of Pierine influence. 

 If we turn to the East we find a precisely similar state of 

 affairs, namely, numerous species of quite differently 

 coloured Papilios, including most of the splendid Ornitho- 

 pteras, which have developed either red spots on the 

 thorax, or on the base of the hind-wing (sometimes to a 

 very remarkable extent), or on both. He who will be at 

 the pains to investigate these facts for himself must, I 

 think, unhesitatingly reject any argument for Diapose- 

 matism in this particular instance. The evidence in 

 favour of an entirely independent development by the 

 Papilios of these distinctive markings appears to be over- 

 whelming. 



