NOCTUID METATHORAX — TREAT 367 



For the present study the choice of the amphipyrine Crymodes 

 devastator (Brace), known in the larval stage as the glassy cutworm,^ 

 was dictated chiefly by coincidence. The work was commenced in 

 midwinter when the only material available in sufficient quantity was 

 a collection of formalin-injected moths of this species which had 

 been made the previous summer. Later, moths of a number of other 

 species and families were dissected for comparison, several, especially 

 for the tracheae, in the fresh condition. Most specimens were partly 

 denuded after removal of wings and legs, then hemisected and trans- 

 ferred to 95-percent alcohol for further dissection. For some pur- 

 poses it was better to have the fixed and hemisected specimen pinned 

 to a block of modeling clay, in air, and moistened from time to time 

 with 50-percent alcohol. Exterior views were drawn from dry, de- 

 nuded specimens. Skeletal parts were studied and drawn from KOH- 

 cleared specimens prepared in the manner described by Richards 

 (1933). Several tympana were excised, cleared, and mounted on 

 slides for special study of the Bugel and associated parts. 



As regards the skeletal homologies of the tympanic region, the 

 views of Richards are accepted provisionally. Richards's ascription of 

 postnotal origin to pockets II and III gains support from the clear 

 serial homology between muscles Ildl, and Illdla, the former arising 

 from a lateral tendon plate or phragma-like process of the mesopost- 

 notum, the latter from what appears to be an anterior extension 

 chiefly of the inner wall of pocket III, referred to by Eggers as the 

 Muskelleiste, and here designated the anterior tendon plate (pis. 2, 12, 

 ATP). Some confusion may arise from Richards's remark concern- 

 ing the Biigel that although it is prominent in Catocala, "none of the 

 other genera examined possess such a structure." Taking the term 

 Biigel to mean (in the noctuids) any apodemal ingrowth from the 

 tympanic frame which serves as a central anchor for the tympanic 

 sensillum or nerve on its course through the tympanic air sac, it may 

 be said that no species thus far examined by the present writer lacks 

 the Bugel completely, and that in most species the structure is fairly 

 prominent, as it is in Crymodes. Histological and physiological details 

 regarding the Biigel cell will appear in another publication. 



The muscle figures were drawn directly from dissections, but are 



2 This species was described by Brace in 1819 as Phalaena devastator. It is 

 figured in Holland ("The Moth Book") as Hadena dcvastatrix. Forbes (1954) 

 assigns it to the genus Septis, which he includes in the tribe Septidini of the sub- 

 family Acronyctinae. The nomenclature used here is that of McDunnough 

 (1938), which is probably familiar to most entomologists. 



