( 42fi ; 



Papilio hellanichus, placing this insect with P. machaon, as all otiier authors • had 

 done, instead of close to P. scaniander. 



In Scndder's work, mentioned above, the genitalia of both sexes have to a 

 certain extent been taken into consideration in distinguishing the species. Messrs. 

 Godman and Salvin followed that line of research, at least with the S genitalia, 

 details of which are figured of nearly all the Central American Papilios in their 

 fiimous work, the Diologia Ccntrali-Amtricaiia. The female genitalia were only 

 referred to cnrsorily in a few instances, inclusive of the bursa copulatrix, which was 

 often fonnd to be different in different species. It was the first fannistic work on 

 tropical insects in which such researches were carried out. These reseaiches have 

 greatly advanced our comprehension of the true taxonomical value of these organs. 

 The iiuthdrs fonnd the genitalia to be excellent guides, in many instances the sole 

 trustworthy guides ; but they recognised also that there are groujis in which the 

 genitalia do not present any tangible differences between the species, while in other 

 instances the organs were observed to be variable. We commenced to work at this 

 problem when the Revision of the Papilios of the Eastern Hemisphere was in 

 preparation (1894). The main results, which we have since repeatedly verified in 

 many groups of Lepidoptera, were published in 1896. t They may be epitomised 

 as follows : 



(1) The majority of species are different in the genitalia of both sexes, a small 

 percentage only showing no distinctions in these organs. Among American Pajjilios 

 P. ariarathes and allies cannot be separated by these organs with certainty, and 

 P. bairdi and pohjxfncs appear to be identical in the genitalia. 



(2) About half the number of geographical forms are more or less distinctly 

 different in the genitalia, at least in the males, the differences being often found to 

 be entirely bridged over by intergradations. 



(3) There is always a certain amount of individual variability in the genitalia. 

 Specimens abnormal in these organs also occur. It requires, therefore, often a 

 series of dissections to arrive at a correct estimate of the distinctive characters 

 presented by the genitalia. There is no individual dimorphism in these organs 

 connected with the dimorphism in jiattern or colour. The only seasonal dimorphism 

 we have come across, though a great number of seasonally dimorjihic species liave 

 been examined, is fonnd in P. xuthus, the spring specimens (from hibernated pupae) 

 differing slightly and not quite constantly in the harjie from the summer sj)ecimens. 

 No such difference obtains in the seasonally dimorphic P. marcelltis. 



It will be observed that the differences in the genitalia, though generally less 

 variable than those of colour and pattern, and often much more striking than 

 wing-difl'erences, require in each case the same careful investigation as colour and 

 pattern, before their true taxonomic value can be pronounced upon. A difference 

 in the genitalia may be specific or varietal, just like wing-differences, t 



A number of American Papilios have been dealt with by Eimer in his 

 treatises on ArthiUlKiKj und VencamUschift bei Schmctterliiigeii (1889 and IS'.to). 

 These essays are of a philosophical nature. As contributions towards Papilio- 

 systematics they are a failure, the researches uot having been intrinsic enough to 



* Burmeistcr, in 1S7S, pliiccd hdlaitichKS iic;ir scamandvr. II uppear.s that be a.ssigned the right 

 pusitiun to it only bceausc lie identified it erroneously with clcotM Gray (1832), wbieh was known to be 

 a near relative tif icamttiuh'r, 



t " Jlechanical Selection," in Xov. Zmil. iii. pp. 420 — 525 (IsutJ). 



X r. Born lias arrived at similar results from a study of the forceps of Cartihui (see Jiuckicit-lior;c 

 xvii. (1900) and «.). 



