45 
subject. 1 will, however, venture this point, that while Dr. Chapman’s 
paper on the phytogeny and evolution of the lepidoptera, is from the 
oval and pupal standpoint, it is also from the only satisfactory stand¬ 
point we can take, if we are to work, as biologists say we should work, 
on embryological characters. There are, however, certain characters 
in the imago which there appears to be no reason for rejecting when 
working in this direction. Comstock separates all the lepidoptera 
into two large divisions by the insect having either a frenulum or a 
jugum. This separation is quite valueless by itself as the jugum is 
not supposed to fulfil the same purpose as the frenulum and there are 
many insects which have neither structure. It is useful, however, in 
that we can trace the jugum to a structure in some neuroptera, and in 
the fact that the origin of lepidoptera from that order is sub¬ 
stantiated by this character taken in conjunction with the pupal 
evidence, and showing that the Jugatae are the lowest of 
the lepidoptera. But, besides the frenulum and jugum struc¬ 
tures, there is that character already touched on, the neuration. 
It is already ceded that the ovum and pupa offer themselves 
for phylogenetically arranging the groups, because oecology can 
play no part in their structure. It thus seems to me that if we can 
satisfy ourselves that the neuration of the perfect insect cannot undergo 
change (ecologically, we are perfectly justified in assigning to it a 
place of phylogenetic value also. Probably in the vast majority of 
individuals oecology plays no part in the neuration, but I cannot 
altogether think that it never does. It is hard to believe that the 
hindwing of some species is not modified by circumstances and outward 
conditions. The members of the curious genus Hirnantopterus afford 
a good illustration. Of the very few members of the genus the 
hindwing shows extra-modification in each species, and point to very 
unstable conditions. Environment of course may be outside the cause 
altogether, but with such closely related species, and occupying so 
completely an isolated position, it is probable that some external agent 
is playing its part. Hampson, in his Moths of India, vol. i., 
remarks about these insects: “ They are degraded forms which have 
arisen from an ancestral type; the veinlet in the cell and vein lc of 
forewings being more or less developed, show that they belong to the 
Zygaenidae and the absence of mouthparts places them in the subfamily 
Phandinae, near Pryeria, while on the other hand they are allied to 
the Psychidae.” We are not told what the degraded forms are 
degraded from, and there is no suggestion. But the species themselves 
show stages of modification, and although the term degraded is used, 
specialised probably is better adapted. With species closely related in 
every way, it is impossible to conceive any other than extreme forces 
acting to bring about modification. Upon this rule Hirnantopterus 
tends to prove that neuration, in the hindwing at all events, cannot be 
of the same value as evidence taken from the ovum and pupa. But 
although the hindwing appears to be capable of undergoing modifica¬ 
tion, and, as a result, neuration undergoing modification, the forewing 
seems much more fixed, and I can think of no parallel case to Iliinan- 
topterus with the forewing. And from this it is not unlikely that in 
the neuration of the forewing we have much more fixed characters, in¬ 
deed, the fact of our detecting so many more modifications in the 
hindwing goes to prove this. Meyrick, writing in the Zoologist, in 
