60 
INTRODUCTION. 
groove internally wliicli receives the tuft within it 
when at rest. The tarsi are always pentamerous, 
the joints usually elongated, the basal one being 
sometimes longer than the tibim. Hepialus Hectus 
is anomalous in this respect, the tarsi being entirely 
wanting in the hinder legs. 
It has been already stated that the wings of the 
night-flying lepidoptera are never held in a vertical 
position when at rest ; but this negative charaeter 
is almost the only general one that can, in this par- 
ticular, be ascribed to them. In other respects, 
their position and bearing are so varied, that the 
distinctions arising therefrom have been sometimes 
emploj'ed to divide the whole tribe into separate 
groups. In many they are parallel to the plain of 
position, or slightly inelined, and the upper pair 
folded along the back in such a manner that the 
one overlaps the other, thus rendering the two an- 
terior margins parallel uith each other and with the 
body, while the imdcr pair m’e folded up beneath 
somewhat after the manner of a fan. It frequently 
happens, in an arrangement similar to this, that the 
internal edges do not overlap but are simply applied 
to eaeh other ; or the internal edges are parallel and 
more or less remote from each other, tearing a portion 
of the back of the abdomen exposed, while the line 
of the anterior edge of the upper wings gradually 
recedes from the body to the hinder extremity, and 
thus forms the side of an isosceles triangle. In many 
instanees the upper %rings meet at their internal 
edges, and are elevated above the body in such a way 
