94 
mens emerged—14 ¢ and 8 9. ‘These emerged in June, with the 
exception of two (which came out in July). 
B (fT: bistortata x 2 T. crepuscularia). Of the other brood of this 
cross (marked 3/3) a fair number of the larvae fed up and pupated 
very quickly, but others fed up slowly, and did not go down until the 
earliest specimens had commenced to emerge ; larvae unhealthy, large 
proportion died. Nine specimens emerged: sh males and three 
females. Four minute specimens—+@ in. (¢), 7¢ in. (22), 1g in 
(12). These small specimens emerged in late June, two normal 
specimens in early June, one on September 29th, and two late in 
October. It may be well to mention here that these tiny specimens 
are not infrequent in inbred 7? dzsfortata. Such a brood as this last 
is practically useless for comparative purposes. 
IV. Crossings obtained from Fybrids. 
Besides obtaining reciprocal crossings of the parent species, pair- 
ings of the hybrids were obtained by Dr. Riding between June 13th 
and 26th, as follows:—(1) ¢@ (¢ 7: bistortata x 2 T. ab. delame- 
rensis) X 9( 8 T. ab. delamerensis x 9 T. bistortata). (2) O(¢ T. 
ab. delamerensis X 9 T. bistortata) x 2 (8 T:. bistortata x 9 T. ab. 
delamerensts). (3) @( 6 T. bistortata x 9 T. ab. delamerensis) x 9 
(3 ZT. bistortata x 2 T. crepuscularia). (4) 8 (é TZ. crepuscularia 
x ¢$ T. bistortata) x 2 (oT. bistortata x 2 T. crepuscularia). (5) 
3 (3 T. bistortata x 2 T. crepuscularia) x 9( 38 T: crepuscularia x 
9 T. bistortata). Of these different crosses twelve pairings in all 
were obtained, eleven of which gave ova, and yet of these eleven 
batches only two were fertile, both crosses of ¢ (¢ TZ. ab. delame- 
rensis X 9 T. bistortata) x 9 (8 T. bistortata x 2 T. ab. delame- 
rensis). Later pairings of ¢ (¢ TZ: crepuscularia x } T. bistortata) 
x 29 (4 ZF. bistortata x 3 T. crepuscularia) also proved infertile. 
Dr. Riding, however, obtained four inbred pairings of ¢(¢ Z. 
bistortata X 9 T. crepuscularia) X 2 (oT. bistortata x 9 T. crepus- 
cularia) ; one of these produced no eggs, another was infertile; the 
two others were only partially fertile. 
In addition to the first crosses already summarised, Mr. Bacot 
obtained the following more or less fertile crossings of the various 
hybrids reared from the already described broods : 
(1) B(S Zab. delamerensis x 9 T. bistortata) x 2 (8 T. bistor- 
tata x 9 T. crepuscularia). Two pairings:—a. June toth; 8. 
August 6th. 
(2) (4 TZ. ab. delamerensis x 2 T. bistortata) x (3 T. bistortata 
x 2? 7: ab. delamerensis). ‘Two pairings on June roth (eggs mostly 
fertile 
ane (3g TZ. bistortata x 2 T. crepuscularia) x 3 (38 T. bistortata 
x 2 ZT. ab. delamerensis). Paired June 11th. 
He further obtained the following inbred pairings : 
(4) 3 (3d T. bistortata x 2 Ti crespuscularia) x 3 (8 T. bistor- 
tata x 2 T. crepuscularia). Four pairings :—a. June roth. 6. June 
