EXPERIMENTS IN HYBRIDIZATION AND TEMPERATURE. 81 



and have scarcely a less number of eggs in their ovaries than is 

 averaged by the pure species. The in-breeding of two of these 

 hybrids resulted in eggs from which emerged a number of larvae 

 (see footnotes 11 and 12), which, however, up to the present, 

 have not been successfully reared. 



Secondly, they have confirmed that the physiognomical 

 aspect of the hybrid will be mainly influenced by the phylo- 

 genetic oldest species. 



Thirdly, subordinate to this law, certain characters found 

 more or less pronounced expression (especially with hybrids 

 of the genus Pygcera), which may be regarded constitutional 

 to the sexes of Lepidoptera, viz. : in the male, a tendency to 

 progressive development ; in the female, conservative tendencies 

 and inclination to retrogress. 



To gain a quick and systematic view of the matter, the 

 following twelve hybrid broods were obtained : — 



Drepaaa 



20. 21 22. 



/ curvat 

 cnrvatnla Bkh. 3 falcataria <5 _ ' faloataria C 



/ ciifvatnla $ \ (5 

 ' faloataria O / 



faloatana L. ? cnrvatula £ ^' / curvataJa (J \ 



' falcataria Q ' Q 



23. 24. 25. 26. 



Preaera " '«" ^fn. S caTtn\& <3 cnrtnla L. <f a nachoreta 3 



ourtnla L. U '^' pigra £ ^^ anachoreta F. Q ^^' onrttila Q 



27, 28. S9. 



/ pigra (5 \ cT / CTirtnla <5 \ 3 / cqrtBla <? \ 3 



Vcnrtula Q ' „ \ piera Q ' _ V anachoreta Q/ 



p V pigra £ / V anachoreta g . 



/ pigra S \ / ourtala (5 \ ^^^ aoaohoreta 9 



\ curtula S ^ 9 V pigra 8 ^ 2 



(^ 



pigra 8 ^ ? 



80. 31. 



onrtnla S \ <? \ J 

 anachor eta q' | ^ anachoreta (5 \( 



p V anachoreta £ / -^ V curtola C 



aoaohoreta Q '*' ourtnla £ 



From a number of pairings of Nos. 22, 27, and 28, a small 

 number of larvae were obtained, but they were never successfully 

 reared. The whole of these creatures showed evident signs of 

 want of energy. The remaining nine crossings were all reared 

 to the imago, some of them in numbers. 



The hybrid of Drepana curvatula <? xfalcataria ? (No. 20) is, 

 as already stated, figured (PI. IV. figs. 5 and 6), being a male 

 and female ; PI. IV. figs. 8 and 9, show a pair of the reciprocal 

 hybrid No. 21. Of No. 20 the males and females emerged 

 together, whereas in No. 21 the male imagines soon emerged, but 

 none of the females developed at once, but hybernated as pupae. 

 This biological difference was already very apparent during 

 pupation. The male individuals only bent round a small 

 portion of the edge of the leaf, fixed to the same in its concave 

 shape by a few small threads on the surface, and changed to a 



EKTOM. — MARCH, 1901. G 



