CROSS-PAIRING OF PAPILIO MACHAON AND P. POLYXENES. 201 



umbellifer-feeding Papilios as P. machaon, from which, however, it 

 differs considerably in the imago as far as coloration is concerned, the 

 body in both sexes being black and only spotted with yellow, whilst the 

 male had large portions of what is yellow in the wing-expanse of l\ 

 machaon taken up with black, and the female both in its larger size and 

 colouring closely resembles that of Eujihoeades troiliis, and that of the 

 black variety of Jasoniachs (/laucus ; all these being, presumably, mimics 

 of Laertias pliilcnnr, the only pharmacophagous and highly-protected 

 Papilionid inhabiting the greater part of the region of which they are 

 denizens. The day was a gloriously fine one, and the pairing, which 

 took place about mid-day, lasted about four hours. The P. machaon, 

 which was an English bred male, was a worn specimen, and had lost 

 almost the whole of the right, and part of the left, antenna. The 

 P. polyxenes was a freshly-emerged female and normal in all respects 

 save in that of size, it being rather smaller than is usually the case 

 with that species. When the pairing was at an end, I segregated the 

 P. polyxenes $ , and was successful in obtaining a fair quantity of aya 

 from her, laid on a growing plant of fennel on June 30th and the two 

 following days. The ova both in shape and colour were indistinguish- 

 able through a magnifying glass from those of P. machaon and P. 

 poly.veneii with which I compared them. They began hatching on 

 July 8th, and all the larvjB had emerged by the 11th. As I wished if 

 possible to obtain a second-brood of my hybrids in 1908, in order to 

 avoid the emergence of the butterflies in the autumn, I forced the 

 larvae in a vinery at a temperature which was seldom if ever uuder 

 85° in the daytime and relatively hot at night; for, had I allowed them 

 to remain out-of-doors, the imagines no doubt would have emerged at 

 too late a period of the year for me to have been able to feed up the 

 resultant larvae. P. polyxenea, I had found before to attempt invariably 

 a second-brood in England, whilst I knew that the hybridizatioii was 

 likely to prove an additional factor in accelerating development. In 

 their early stadia I found the larvae in all respects like those of their 

 parents, which, in turn, I am unable to distinguish between at this 

 period of their lives, both being subject to much variation. In the 

 penultimate instar the hybrids seemed to me somewhat less yellow than 

 those of P. polyxenes, and generally resembling P. machaon. The 

 full-grown larva, however, was exactly like neither. It was larger 

 than that of the average P. machaon, being identical in size with that 

 of P. polyxenea, and had the bluer-green ground colour of the latter, 

 but the chrome-yellow spots of P. polyxenes and the red ones of 

 P. machaon, were replaced by pale orange ones, which were larger than 

 those of the P. polyxenes larvae I have met with, and ahnost entirely 

 broke up the black bands as in some specimens of /'. uiadtaon. The 

 first larvae spun up for pupation on July 26th. 



The resulting pupje resembled typical P. polyxenes pupte in all 

 respects, and were not in the least like those of /-". machaon, either in 

 shape or in colour wherever a difference presents itself between the 

 parent strains. They even followed those of /-". polyxenes in the longer 

 and slenderer stays of the thoracic girdle. The first imago, a male, 

 emerged on the morning of August 12th, the pupa' having been kept 

 in the vinery at the same heat as the larvre, save that the weather 

 outside had turned colder. It was followed by two others in the course 

 of the week (14th and 17th), both being males. Although T secured 



