( 696 ) 



form of P. philolaus. There is no strncturul differpiice between P. rrniticles and 

 jiliilolaus, xanticles having all the jipiuliarities in tlie structure of the scent- 

 organ, the genitalia and legs which we have mentioned nnder P. ]>liilolaii.<<. In 

 pattern the two insects are well separated. However, we must bear in mind that, 

 /'. p/iilolaiis being known to occur as far south as Nicaragua, and xanticles having 

 been found only in Colombia and Panama, there is a geographical gap between the 

 two Pajiilios, where possible an intermediate form exists which has as yet escaped 

 observation. 



The fact that the extended-black P. philolaus and the much less extended- 

 black P. xanticles are two closely related species, if they are not geographical 

 varieties of one species, appears to us to upset one of those "laws " of development 

 established on insufficient evidence by Eimer and accepted by others. In Ortho- 

 genesis, p. 401, Eimer comparing the characters of philolaus with those of the 

 various seasonal forms of marcellus {ajax, auct. non Linn6) comes to the conclusion 

 that the black bands of philolaus are strongly developed because philolaus is a 

 more southern insect than marcellus. However, if high temperature and moistnre, 

 as Eimer says, were the real causes which have turned the less extended-black 

 ancestral philolaus into the extended-black present-day philolaus, then the ally 

 of philolaus which lives in a hotter and more moist climate than philolaus itself, 

 ought to be more extended-black than philolaus. We find, on the contrary, that 

 P. xanticles from the coast of Panama and the north coast of Colombia is far less 

 black than philolaus from Nicaragua and the countries northwards, inclusive of 

 Mexico, and even than the North American marcellus. 



Eimer makes another mistake when talking of the lines of development of 

 P. philolaus and P. marcellus. He calls tlie black form of philolaus — Eimer did 

 not know that this black form is restricted to the female sex — as being arrived at by 

 extension of the black bands. That is not correct. The pale bands have not become 

 narrower and narrower until they finally disappeared, but the i)ale bands have 

 become suppressed by the scaling turning black. This assumption of black colour 

 on the part of the scales of the pale bands is a new kind of development (see 

 P. ph. ?-f. niger), the black wing of these females being not at all the final result 

 of Orthogenesis, i.e. of a gradual widening of the black bauds. 



The Papilio plaesiolaus Stand. (liSS4), which is the same as xanticles, is treated 

 by Eimer, I.e., as being a variety of arcesilaus, a very different species. However, 

 Eimer knew xanticles only from Bates's figure and description, and plaesiolaus 

 from Staudinger's description. 



In tlie Tring Museum 8 cJ cJ from Panama. 



In coll. F. D. Godman a series of males and the only known female. One of 

 the males, from Manaure, S. Martha, has the yellow discal areas of both wings and 

 the snbmarginal spots of the forewing enlarged. 



144. Papilio oberthueri spec. nov. (PI. VI. fig. 25). 



i. Body, antenna, and legs essentially as in /'. jthilolaus. 



Wings, upperside : less deej) black than in 1'. jihiloluu.s, (lie scales nearly all 



mii- or bisinuiite. Forewing seniitran.sparent distally, jr.ile bands white, proximal 



ones greenish, snbmarginal spots also greenish ; these bands broader than in 

 P. philolaus ; second pale band about two-thirds the width of the black band 

 situated distally of it, sixth band extending to R-, being separated from the white 

 discal area only by the black vein R-, costally a little more distal in position than in 



