92 
of brood 1 (above). They emerged between June 7th and June 
24th, 1897. These exhibit the dead grey colour and ill-developed 
markings that characterise the second brood of the species, which is 
known as ab. consonaria, St. These are specially useful as showing 
the progeny of Z. dzstortata, uncrossed by Z. crepuscularia. ‘The 
broods are those from which the parents of the hybrids were selected. 
The specimens exhibited, and used by Mr. Bacot as the parents 
from which his hybrids were obtained, were from the same localities 
as those used by Dr. Riding, viz. Clevedon (Somerset) for Z! dzs- 
tortata, and York district for 7° crepuscularia. 
Il. Aybrids obtained by Dr. Riding. 
RECIPROCAL CROSSINGS OBTAINED.—The reciprocal crossings 
obtained by Dr. Riding were as follows :—Fertile reciprocal crosses 
from broods 1, 2, and 3 (above), viz.— 
1. Z. bistortata 3 x T. ab. delamerensis 2 .—a. Paired March 
rith ; ova deposited March 15th; hatched April 26th to 27th. 
2. T. ab. delamerensis @ x T. bistortata 2 .—a. Paired March 
gth ; ova deposited March r4th; hatched April 18th to roth.—B. 
Paired March oth; ova deposited March 13th to 14th; hatched 
April 18th to roth. 
3. ZT. bistortata 8 xX T. crepuscularia 2.—u and B. Two pair- 
ings on March 17th; ova deposited March 2oth to 22nd; hatched 
April 25th to 27th. 
4. T. crepuscularia 8 x T. bistortata 3.—a. Paired March 7th; 
ova deposited March 16th; hatched April 21st to 22nd. 8. Paired 
March r4th ; ova deposited March zoth ; hatched April 22nd to 23rd. 
Crossings that failed were—(1) 7: ab. delamerensis @ x T. bis- 
tortata ° , two pairings, February 28th and March rath. (2) 7° crepus- 
cularia & x T. bistortata 9, three pairings, March 7th, roth, r4th. 
Hysrips.—1. Hybrids between 8 T. bistortata (Clevedon) and 2 7: 
ab. delamerensis (York).—No. 1 in list above. One batch of eggs 
hatched April 26th to 27th; too imagines emerged between June 
12th and October 22nd, 1897; 48 ¢ and 52 2. 
u. Hybrids between 3 T. crepuscularia ab. delamerensts (York), 
and ° T. bistortata (Clevedon).—No. 2 of above list. Two batches of 
eggs obtained ; hatched April 18th to 19th. The two broods were 
fed up together, the imagines exhibited being a mixture of both 
broods. Sixty-one imagines are exhibited (60 ¢ and1 92). These 
emerged between June 12th and September roth, 1897. 
These two crosses represent the reciprocal crosses of 7? d¢stortata 
and 7. crepuscularia ab. delamerensts. ‘The percentage of a form 
approaching ab. dedamerensis in the two crossings are 60 and 4o per 
cent. respectively ; the crossing in which 7: dzstorfata was the male 
parent has produced by far the larger and more vigorous offspring. 
it. Hybrids between g T. bistortata (Clevedon) and 3 T. crepus- 
cularia (York).—No. 3 of above list. Two batches of eggs ob- 
tained ; hatched April 25th to 27th; larve fed up together. 121 
