60 INTRODUCTION. 



groove internally which 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 tibiae. 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 character 

 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 

 employed to divide the whole tribe into separate 

 groups. In many they are parallel to the plain of 

 position, or slightly inclined, 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 with each other and with the 

 body, while the under pair are 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 each other ; or the internal edges are parallel and 

 more or less remote from each other, leaving 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 

 instances the upper wings meet at their internal 

 edges, and are elevated above the body in such a way 



