3 I 2 LEPIDOPTERA CHAP. 



smaller part, the meso-scutellum behind. In front of the scutum 

 there is a piece termed prae-scutum by Burgess. It is usually 

 small and concealed by the front part of the scutum ; but 

 in Hepialus it is large and horizontal in position. It is of 

 importance as being the chief point of articulation with the pro- 

 thorax. The scutellum is more or less irregularly rhomboidal in 

 form ; its hinder margin usually looks as if it were a lobe or fold 

 placed in front of the base of the abdomen or metathorax, accord- 

 ing to whether the latter is concealed or visible. In some of the 

 higher forms this meso-scutellar lobe is prominent, and there 

 may be seen under its projection a piece that has been called 

 the post-scutellum, and is really the base of the great meso- 

 phragma, a chitinous piece that descends far down into the 

 interior of the body. In addition to the front pair of wings the 

 inesothorax bears on its upper surface another pair of appendages, 

 the tegulae : in the higher forms they are of large size ; they are 

 fastened on the front of the inesothorax, and extend backwards 

 over the joint of the wing with the body, being densely covered 

 with scales so that they are but little conspicuous. These 

 appendages are frequently erroneously called patagia, but have 

 also been called scapulae, pterygodes, paraptera, and shoulder- 

 tufts, or shoulder-lappets. The lower surface of the inesothorax 

 is much concealed by the large and prominent coxae, but the 

 sternum and the two pleural pieces on each side, episternum and 

 epimeron, are easily detected. The area for attachment of the 

 anterior wing on each side is considerable, and appears to be of 

 rather complex structure ; its anatomy has been, however, but 

 little studied. 



The METATHORAX is small in comparison with the preceding 

 segment, to which it is intimately co-adapted, though the two 

 are really connected only by delicate membrane, and can conse- 

 quently be separated with ease by dissection. The metanotum 

 consists of (1) the scutum, which usually appears externally as 

 an anterior piece on each side ; (2) the scutellum, forming a 

 median piece placed behind the scutum, which it tends to 

 separate into two parts by its own extension forwards. In order 

 to understand the structure of the metathorax it is desirable to 

 dissect it off from the larger anterior segment, and it will then 

 be found that its appearance when undissected is deceptive, 

 owing to its being greatly arched, or folded in the antero- 



