ATTACID/E. 291 



hybernating m the pupal stage and maintaining itself as a distinct 

 form for some time. Berce also obtained hybrids of A. yamamai 

 X pernyi, and 19 of these cocoons came into the possession of 

 Wailly in 1875 (Eniom., xiii., pp. 155 et seq.). From these cocoons 

 only 1 imago, a 2 , emerged, and this paired with a male A. 

 pernyi, the larva, when hatched, being entirely blark like those of 

 A. pernyi, and bearing no resemblance to those of A. yamamai. 

 Wailly does not tell us what special characters were developed later ; 

 one suspects that some signs must have remained of the yamamai 

 ancestry. About 1878, the Bombay silk-spinners are said to have 

 hybridised the Indian Tusser silkworm {Antheraea mylittd) with A. 

 yamamai, whilst Bourdier, in 1878, evidently obtained fruitful 

 hybrids between A. pernyi and yamamai, which he called A. hybr. 

 perny-yama and says : " This fruitful hybrid has the immense 

 advantage over the parents of being perfectly hardy , it will resist 

 a temperature of o° C, and will eat even dried leaves if they are 

 not brittle; a second brood may be obtained each year, if the breeder, 

 by artificial means, hastens the emergence of the moths from the 

 hybernating cocoons." Wailly further notes that for several years 

 he has obtained crossings as follows : pernyi $ x polyphemus 2 ', 

 cecropia $ X cynthia 2 , several times ; cecropia $ X gloveri 2 ; 

 cecropia $ X polyphemus 2 , several times ; pyri x cecropia, but that 

 in every case the eggs have proved infertile. Wallace cites {Darwinism, 

 1 889, p. 163) from Quatrefages, a case of fertility inter se in Attacus hybr. 

 cynthia X arrindia. Watson notes (Ent., xxvi., p. 174) a reputed 

 fertile hybrid between Attacus cynthia and A. ricini, but questions 

 whether it be, indeed, a hybrid, asserting that it is " now conclusively 

 proved that ricini is merely the Burmese local polyvoltine or many- 

 brooded variety of the common cynthia" and concludes that even 

 if crossings of cynthia and ricini are perfectly fertile, it is only a 

 cross between a species and its variety. He further records [loc. cit., 

 p. 176) Antheraea mylitta crossed with A. yamamai, and A. pernyi 

 with A. mylitta. Heyer notes (Soc. Ent., xiii., pp. 137 — 138) pairings 

 as follows : 



(1) Platysamia cecropia $ x Satu mia pyri ?. (2) Platysamia cecropia $ x 

 P. californica (ceanothi) ? . (3) Platysamia californica (ceanothi) <? x P. 

 cecropia ? . (4) Platysamia ivatsoni J x P. cecropia ? . (5) Platysamia heyeri 

 $ X P. cecropia ? . (6) Platysamia cecropia $ x P. ivatsoni ? . (7) Platy- 

 samia cecropia £ x P. heyeri ? . (8) Platysamia ivatsoni 3 x P. heyeri ? . (9) 

 Platysamia heyeri <? X P. ivatsoni ? . (10) Telea polyphemus $ x Antheraea 

 pernyi ?. (11) Antheraea pernyi <? X A. yamamai ?. 



Combination 1 succeeded in only two cases, with sacrifice of 

 considerable material, 4-1 1 each in one case, 2-3 in several. All 

 the eggs from the crosses polyphemus X pernyi and cecropia X pyri 

 were infertile. The pernyi laid a normal number, one of the pyri 

 perhaps half the normal number the other only one egg. Both the 

 fresh and vigorous pyri $ s died within an hour after ovipositing, 

 a thing which Heyer never observed in normal pairings among 

 pyri. 



At the meeting of the Entomological Society of London, July 7th, 

 1886, Wailly exhibited some remarkable hybrids between Platysamia 

 cecropia and P. californica (ceanothi), but one finds a much fuller account of 

 the hybridisation of some of the American species {Ent., xxvi., pp. 176 — 



