83 
in Agta as in Automeris, upon which latter type Ag/a constitutes a 
very small advance. Both forms must have had a common ancestor. 
If we now turn to Hemzleuca we find that this fulfils every require- 
ment, which Aga disappoints, of the Saturnian type of wing. 
Already veins IV 1 and IV 2 are furcate upon a long stem. This 
stem represents, not the cross-vein between IV 2 and IV 1, but that 
portion of the cross-vein lying between IV 1 and the radius, exactly 
as in Saturnia and Aftacus. But on the secondaries vein VIII is 
retained. Now this is just what we should expect from a generalised 
Saturnian form, because vein VIII of hind-wings is retained by most 
Lepidoptera, and is dropped by specialisation. The corresponding 
form for Agda and Auwtomeris, retaining vein VIII, we find in the 
Citheroniadee, which latter take the place of /emz/ewca in this cha- 
racter upon the Aglian phylum. ‘The Citheroniadee are of interest 
in this controversy, because here vein IV 1 leaves the cross-vein to 
become absorbed by the radius outside the cell. This change is one 
impossible to be entered upon by AHemz/euwca and the Saturnian type, 
because IV 1 and IV 2 are here upona long stem, and cannot reach by 
any means the radius to ascend it. ‘The two veins gradually approach 
and meet upon this long stem, and this is their evolutionary direction 
and progress. But in Ag@a and Automeris vein IV 1 is free to ascend 
the radius, because it has not left the cross-vein. ‘The Citheroniadee 
run parallel in this development with the Smerinthine, in which the 
movement of IV 1 from the cross-vein to the radius is normal. 
The genus Hemzleuca appears to me to represent the ideal of an 
ancestral form of Saturnia. It fulfils every requirement we should 
demand. 
To place Hemtleuca with Automerts is a palpably hazardous under- 
taking. Hemrleuca has retained vein VIII, while Awfomerzs has lost 
it. Hence Aztomeris should also show us a more specialised type in 
the disintegration of the media, which it does not. Indeed, it shows 
us a totally different type. ‘To derive Aufomeris from Hlemzleuca, the 
stem of IV 2 and IV 1 must retreat backwards, and the plan of evolu- 
tion be entirely changed. How can the stemless 4u/omervs be related 
to the stemmed Hemz/euca? ‘The ancestral type of Aufomeris had un- 
doubtedly vein VIII, but it had evidently a vertically closed cell, and 
could show no disposition to form a stem out of the cross-vein 
between IV 1 and the radius. It is inconceivable that these two 
opposed evolutionary types could have been loosely held by acommon 
ancestor so near in time to the present forms as to excuse our placing 
them in one “family.” More than this, not the faintest reason 
can exist for the specialist to bring them so together upon neurational 
grounds. If this is so, and so I believe it to be, then either the 
neuration, as a source upon which we can rely to form natural family 
groups, must be disregarded, or it must replace, as a better authority 
for classification, the larval characters as presented by Dr. Dyar. 
While the general character of the wings of Agdza, Automeris, and 
Citheronta is the same in being confined, rigid, the veins not spread- 
