March, '08] ENTOMOLOGICAL NEWS. 137 



examination showed that they were not lateral or dorsal ex- 

 cresences but true wing-pads occupying positions exactly simi- 

 lar to those of the wing-cases of the Tcncbrio pupa. Since this 

 larva was observed Professor Heymons has been able to find a 

 number of larvae of the same species presenting the same 

 anomaly, and at the recent Zoological Congress at Boston he 

 exhibited several such specimens. 



Soon after the appearance of Heymon's first note, Mr. Busck 

 exhibited before the Entomological Society of Washington,! 

 six larvae of the Dermestid, Anthrenus varius, each of which 

 showed well marked wing-pads on the second and third thoracic 

 segments. 



In the summer of 1902 one of our students, Mr. P. B. 

 Powell, who was breeding large numbers of Coleopterous 

 larvae, discovered the phenomenon in the case of one of a 

 number of larvae of a common Pyrochroid, Dendr aides cana- 

 densis. This specimen showed the hinder pair of pads the 

 larger while the contrary was true of the cases reported by 

 Heymons. The larva was apparently in the last stage, and 

 exhibited various other abnormalities which will be referred 

 to later. 



At first sight it seems strange that all of the individuals 

 presenting this peculiarity are coleopterous larvae but this is 

 readily explicable when we consider the anatomical relations 

 of the developing wings in this group. The best known type 

 of wing development among holometabolous insects is what 

 Tower has designed the "enclosed type" (the Pieris type of 

 Gonin). In this the wing-bud invaginates and finally comes to 

 lie in a closed sac connected with the body wall by a short, 

 slender peduncle. Thus it lies wholly within the body cavity. 

 On the other hand, the researches of Tower, '03, Powell, '04, 

 and others, have shown that in Coleoptera the dominant type of 

 wing development is that which Tower has designated the 

 "simple type." Here as in the hcterometabolous forms the 

 wing rudiment is 'not sharply marked off from the body hypo- 



+Busck, Aug. '97. Larvae of Anthrenus varhts, showing wing pads. 

 Proc. Ent. Soc. Wash, iv, p. 123. 



