398 SECTIONAL TRANSACTIONS.—D. 
8. Dr. J. W. Hestop Harerison.—On Hybrids between British and 
Canadian Lepidoptera. 
The hybrid unions brought about fall into five groups :— 
(1.)—(a) Oporabia omissa (mihi) 9x O. autumnata 3. 
(b) Oporabia omissa 2 x F, (O. filigrammaria? x O. autumnata 3) 3. 
(c) F, (0. filigrammaria 2 x O. autumnata 3) 2 x O. omissa 3. 
(d) F, (O. fiigrammaria 2 x O. autumnata 3) 2 x O. omissag. 
(e) O. filigrammaria 2x O. omissa 3. 
The outstanding feature here was the discovery that the species named here 
Oporabia omissa, and generally called O. dilutatain America, was quite a distinct form 
more closely allied to O. autumnata. It differsfrom that form in the obscurely hooked 
valves of its male genitalia, its size, wing pattern and larva. All the crosses listed, 
with others of more complex origin, were reared and both sexes obtained, but attempts 
to secure an F, generation failed, owing to the sterility of the F, hybrids. Segregation 
of autumnata and filigrammaria characters was noted in crosses (0), (c) and (d). In 
all the broods structural abnormalities in the way of interpolated segments were 
noted in the larvae. 
(II.)—(a) Poecilopsis rachelae 9 x Lycia hirtaria 3. 
(6) Nyssia zonaria 9x P. rachelae 3. 
(c) P. rachelae 2x N. zonaria g. 
Here, again, only F, broods were possible. An important fact was the appearance 
of intersexes in cross (c). Structural defects similar to those mentioned above were of 
free occurrence. 
(IIL.)—Ennomos quercinaria 2 x E. subsignaria g with back crosses. 
The F, 9, proving fertile, was back-crossed on both parent species when segregation 
in wing colour was observed in the offspring. At the same time the reciprocal pairing, 
repeatedly produced, yielded eggs which failed to hatch. 
(IV.)—(a) Orgyia antiqua 2 x O. badia J (Brit. Columbia and Oregon). 
(b) O. badia 2x O. antiqua 3. 
(c) O. antiqua 2x O. nova 3 (Montreal, Nova Scotia, Maine). 
(d) O. nova 2x O. antiqua 3. 
This set of pairings was secured with extreme facility, yet the resulting ova only 
hatched when the 2 parent was of European origin, the test matings exceeding 100 in 
the critical cases. , broods were reared from (a) and (c). In the cross (a) the melan- 
ism introduced by the badia 3 proved dominant, and a normal 3 ; 1 ratio appeared in 
the F, batches. On the other hand, in the cross between the Eastern insect and the 
European form, a persistent blend with but little indication of segregation in F, and 
back crosses was the result. 
(V.)—(a) Orgyia leucostigma 2 x O. antiqua 3. 
(6) O. antiqua 2 x O. leucostigma 3 (Toronto, Montreal). 
(c) O. vetusta2 x O. antiquadg. 
(d) O. antiqua 3 x O. vetusta? (California). 
In all these cases eggs were duly laid, but none hatched. 
9. Mr. A. D. Pxracocx.—Sexuality in the Saw-fly (Pristiphora 
pallipes, Lep.): a Study in the Evolution of Parthenogenesis. 
In England, and apparently in Canada, P. pallipes is almost completely 
asexually female-producing, as out of 600 individuals bred during three years 
only four were males—one from stock, two from eggs treated by immersion in 
magnesium sulphate (sol. 2 per cent.), the fourth from eggs treated by immersion 
in warm water (30° C.); the effects of these experimental conditions upon male 
production and sexuality are undetermined; male sexual instincts are not so 
patent ag in other species; the females ignore the males (a-dechandry), but a 
single apparently genuine pairing was at last obtained; the paired female laid 
twenty-two eggs, nineteen pupe were reared, and seventeen females derived to 
date (May 30). Possible explanations of this thelyotoky are (1) ineffective pair- 
ing; (2) unfertilised eggs; (3) the chromosome complex of the possibly fertilised 
eggs permits the production of females only, of nature similar to Bridges’ 
