294 THE ZOOLOGIST. 
and a vein once lost can never be regained; but of course the 
loss may have, and apparently has, taken place independently in 
more than one line of descent. The whole of the remaining 
Lepidoptera may then be classed in two groups (Psychina and 
Pyralidina) which normally retain this vein, and four others 
which have entirely lost it. 
The Psychina are a group of families of unspecialized type, 
which in fact approach the T%neina so closely as not to be 
separable as a whole by any single character, though each family 
considered by itself is so separable ; at the same time the four 
families composing it are nearly related together in their lowest 
forms, and may therefore be regarded as parallel developments. 
Kven the markings of the wings show this want of specialization, 
as they are, when present, irregular and without definite type of 
arrangement, and all the families show a marked tendency (in the 
Psychide becoming a fixed character) to produce thinly-scaled or 
semi-hyaline unicolorous forms. Itis probable that this indicates 
approximate relationship to the Mumea group of the Tineide, to 
which the Psychide also display their affinity by their apterous 
females and the case-bearing habit of the larva; on this ground 
they have even been included together in the same family, but 
the true Psychide are always distinguished by the anastomosing 
subdorsal veins of the fore wings. The Zygenide include many 
large butterfly-like forms, brilliantly coloured with metallic blue, 
crimson, and white ; the short, stout, often tuberculated and rather 
hairy larve are of an early type, and though apparently very 
different in form and habits to the Psychide, both are probably 
the modified descendants of internal wood-feeders. The Hetero- 
geneide (Limacodide of some) are remarkable for their larve, 
which are an exaggeration of the Zygenid type, the legs being 
often very short and retractile, so that the larva appears to be 
appressed to the leaf like a slug, whilst the dorsal tubercles are 
often developed into clusters of stinging spines; and for the 
small hard oval cocoons, which open by a lid. The tibial spurs 
of the imago are long, as in the Tineina generally, whilst in the 
allied families they are very short or absent, but there is here 
probably some connection with bulk or weight. Finally, the 
Zeuzeride, whilst structurally related to the Psychide, show by 
the wood-feeding habit of their larve and other characters 
