452 BRITISH LEPIDOPTERA. 



such a full, velvet colour as in S. ocellata, but [which] is always 

 wanting in A. populi. The colouring of head, thorax, abdomen and 

 legs approaches more to that of S. ocellata." 



Sexual dimorphism. — The -hybrid S. hybridus has, in the $ s, 

 antennae extremely like those of $ S. ocellata. Those of a quasi- 

 ? specimen (posted, p. 453, gynandromorph 0) are ? , but with a 

 considerable display of the $ hairs. These are most fully 

 developed close to the scaling, and are, in places, almost 

 typical $ ; over the more ventral portions of the antenna they 

 are largely wanting, and are, when present, sparse and shorter than in 

 the $ (Chapman). 



Gynandromorphism. — House notes {Trans. Ent. Soc. Lond., iii., 

 1st ser., p. 194) of certain S. hybr. ocellata X populi that he reared, 

 that " nineteen larvae became adult, and in August twelve of the 

 imagines came out perfect .... The power of reproduction is 

 completely lost, as they appear to be as nearly intermediate between 

 the sexes as between the species ; they evidently partake of the nature 

 of both sexes"; as proof he states that "every newly-emerged insect of 

 the genus Smerinthus on being touched discharges copiously a fluid, 

 which, in the male, is pure white, and in the female of a yellow or 

 ochre colour, whilst these hybrids discharged, at the same motion, 

 first the white and then the other fluid quite distinct, and this compound 

 discharge was quite uniform in every specimen, which is never the 

 case in any true species or sex." Westwood states (loc. cit., p. 195) 

 that two of these specimens submitted to him were males so far as 

 related to their external organs, and adds (p. 202) that in all gynan- 

 dromorphous A. populi recorded up to that time the right side was 

 cT and the left ? . Adamson writes (Ent. Weekly In tell., iv., 

 p. 127) of a brood of hybrid S. ocellata x populi that, in general, the 

 sexes were more or less mixed, but he had one " such a decided male * 

 that he was inclined to see if it would breed," and further noted that 

 he had observed many of the peculiarities referred to by House with 

 regard to their sterility. Kirby observes (Ent., xiv., p. 253) that he 

 was under the impression that gynandromorphism was the usual 

 character of hybrid ocellata X populi. We are disinclined to this view, 

 as Mr. Kirk, who reared ten imagines in August 189c, sent us 5 

 which we still possess, and which, though intermediate between the 

 species, are apparently distinct enough as to sex, consisting of 4 males 

 and 1 female (Ent. Rec, i., p. 203). On the other hand, Bacot reared 

 three imagines in 1896, and their genitalia were examined by Pierce, 

 who reported (Ent. Rec, x., p. 188) that those of the $ s were pretty 

 normal, but those of the °. showed many marked 3 characters. He 

 notes (Ent., xxix., p. 374) that of the 3 specimens the 2 males, although 

 perfectly distinct from the male parent, had perfectly formed genitalia, 



* Standfuss' opinion as to the general failure of the female hybrids ot the 

 Attacids {antea, p. 300) to produce ova, and the large percentage of gynandro- 

 morphous examples among the apparently female examples, whilst the males were 

 capable of pairing with females of either of the parent sex, is supported by Pierce 

 with regard to S. hybr. ocellata x populi, for he notes [Ent. Rec., x., y. 1S9) that 

 whilst the only apparently female example was gynandromorphous, and evidently 

 incapable of reproduction, the hybrid males might cross again with a ? of either of 

 the parent species. Chapman notes that in the ? pupse of Bacot's brood of S. 

 hybridus the sexual organs showed considerable tendency towards a confusion of the 

 sexes, those of the $ s not differing greatly from those of A. populi (see postea, p. 458). 



