Explanation of Plate XL. 
Fia. 13. Offspring of 1. Emerged Dec. 1, 1911. Shows more distinct 
trace of “tail”? on margin of 
hind-wing. 
14. = - “a Dec. 2, 1911. Shows still more 
distinct trace of “tail’’ on 
margin of hind-wing. 
15: pA an = Dec. 2, 1911. Shows faint trace 
of “tail”? on margin of hind- 
wing. 
The degree of development of vestigial tail may be estimated 
by comparing figs. 11-15 with 9, 10, 30, and 38. 
16-30. Brood D (= Family IV, W. A. L., described in Proc. 
Ent. Soc., 1912, pp. cxxxi-cxxxiv). 
16. Parent, from same locality as 1, May 1, 1912. 
The pupe of this brood were exposed to temperature much 
reduced by ice, with a view to ascertaining if shock 
would cause more of the female imagines to revert to 
the ancestral tailed condition, than is the case with 
Family 1 (see specimens 11-15). Traces of tails can 
be seen in specimens 17-21, but no better marked 
than in 11-15 which were not treated with ice. It 
must, however, be remembered that four other families 
reared in a normal temperature by Mr. Lamborn 
(loc. cit. pp. Xii—xvil, Cxxxi-cxxxiv), showed no trace of 
“tails” ; also that 17-20 exhibit a squarish outline rather 
more markedly than 11-15, an appearance due to the 
reduction of all undulations along the margin of the 
hind-wing except the one that represents the “‘ tail.” 
17. Offspring of 16. Emerged June 6, 1912. Shows trace of 
“tail”? at the angle of the 
squarish outline of hind-wing. 
18. aa ‘5 a June 7, 1912. Shows trace of 
“tail” at the angle of the 
squarish outline of hind-wing. 
19. Ai is Ps June 7, 1912. Shows trace of 
“tail” at the angle of the 
squarish outline of hind-wing. 
20. 54 a ee June 7, 1912. Shows trace of 
“tail” at the angle of the 
squarish outline of hind-wing: 
Pile st Es a June 7, 1912. Shows faint 
trace of “ tail.” 
22. Fe o ras June 5, 1912. 
