1895.] | The Classification of the Lepidoptera. 255 
In Hepialus humuli (see fig. 5, plate XVII) the mesonotum 
is relatively larger, compared with the metanotum, than in 
Micropteryx, and there is correspondingly more of a difference 
of outline between the two segments, but the thorax is still dis- 
tinctly a generalized one. The metanotum is about one-half 
as long as the mesonotum. 
Nowhere else among Lepidoptera have I found so general- 
ized a condition of the thorax, as shown by the Jugate, unless 
it be in the Tineina, where, indeed, among all Frenate, it 
would be expected. In Tinea vestitella the thoracic structure 
appears to be in a very generalized state, although the shape 
of the sclerites differs much from that in the Jugate. 
An additional point of interest is adduced by a comparison 
of the thorax of the Jugate with that of the Trichoptera. A 
striking resemblance is apparent, as is illustrated in figures 4 
and 6, one being the dorsal aspect of the thorax of Micropteryzx 
unimaculella, and the other that of Hydropsyche phalerata. This 
suggests again the affinity of the Lepidoptera, through the 
Jugate, with the Trichoptera. ` 
The patagia of the mesothorax exhibit an interesting 
specialization following closely the development of the flight 
function as indicated by the wing venation and the thoracic 
structure. The patagia probably function as shields or pro- 
tective coverings for the insertions of the front wings, the thin 
lobe curving around the base of the fore-wing in a way well 
calculated to protect this unchitinized and vulnerable portion 
of the moth’s body. In the swift-flying sphinges the patagia 
acquire a remarkable development, extending posteriorly 
almost to the hinder margin of the mesoscutum. In the more 
generalized luna the patagia are much less developed, and in 
the Jugate the patagia are very small and inconspicuous. 
The patagia are present also in the Trichoptera, and are strik- 
ingly like the equivalent processes on the Jugatæ. 
A careful study of the thorax of the Lepidoptera must cer- 
tainly be rewarded by suggestive results. 
As to the kind of characters which these drawn from the 
wing-clothing and thoracic structure are, I refer to the para- 
graph at the beginning of this paper quoted from Professor 
