BY K. ILLIDGE AND AMBROSE QUAIL, F.E.S. 165 



other, but, when examined closely, we find sufficient points of 

 distinction between the groups. 



The Hepialid pupa is remarkably cylindrical, Cossidae are 

 not so. Hepialidae have dorsal and ventral segmental spines, 

 Cossidae have the dorsal spines only. The Hepialid antenna is 

 diminutive, reaching only to the " knee " of 2n i leg, in fact 

 that portion of the antenna which extends beyond the pro-meso- 

 thoracic suture is half its entire length. The Cossid antenna 

 reaches to fully half the wing margin being some four times the 

 length of the basal portion. The ancestors of these groups had 

 comparatively short pupal antennae, and if Cossidae are derived 

 from progenitors with antennae like those of typical existing 

 Hepialidae, then the latter are lower in the evolutionary scale 

 than Cossidae, which will have specialized in having developed 

 antennae of greater length. 



The Lepidopterous pupa has its appendages — legs, wing- 

 cases, etc., extending beyond the thoracic segments downwards, 

 adherent to certain abdominal segments which become incor- 

 porated with more or less fixity, so as to lose their individual 

 movement ; the terminal (anal) segments likewise become one 

 coherent mass, in varying number, and movement of the pupa 

 is thus confined to the intermediate segments, of which the 

 incisions remain free and functional. Dr. Chapman has pointed 

 out the importance of this structural character, in classification.! 



The wing cases of Hepialidae adhere to the abdominal 

 segments 1 and 2, that they have become integral parts of the 

 anterior mass is shown in that the spiracle of 2 is subdorsal, 

 and on dehiscence they (the wing cases) still adhere to those 

 abdominal segments. In Hepialidae the free segments are 



5 8, 4, 5, 6, 7 ; $ 3, 4, 5, 6. 



The Cossid spiracles are normal in position, and on dehis- 

 cence the appendages lose their apparent fixity to the abdominal 

 segments, remaining attached only by the inner membrane of 

 3rd legs and hindwings, the disseverance exposing to view the 

 abdominal spiracles (1 and 2) in normal position, until then 

 covered by the wing cases. In Zeuzerinae the free segments are 



J 3, 4, 5, 6, 7 ; ? 3, 4, 5, 6. In Cossidae the free segments 

 are J 4, 5, 6, 7, 2 4, 5, 6. In respect of incorporation of the 

 numbers of abdominal segments into the anterior mass Hepia- 

 lidae are the lowest, there being a tendency in Zeuzerinae to 



t Trans. Ento. Soc. Lond., 1892. 



