8 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



8. Freedom of movement of head and thoracic segments secured 

 by elastic membranes (Pierce, Acroschismus pallidus Brues). (See 

 pi. 5, fig. 7.) 



9. The occasional presence of a mesostigmatal protecting lobe 

 (Pierce, Acroschismus species). (See pi. 5, fig. 4'.) 



10. a, Wings in form of quadrant, folding longitudinally, veins 

 radial. (See pi. 1, fig. 2.) b, The movement of wings and elytra in 

 unison, as contrasted with the stationary character of coleopterous 

 elytra during flight. 



11. The permanent exsertion of the male genital organ (oedeagus), 

 and the entire absence of female external genital organs (Pierce, Craw- 

 fordia pulvinipes, Acroschismus species, Apractelytra schwarzi; Per- 

 kins, 1905, Ilalictophagusf 'species, Elenchus species). (See pi. 2, fig.6.) 



12. Isolation of posterior and middle intestines in male and absence 

 of latter in female (Nassonow, 1892 d, Xenos vesparum Rossi). 



13. Nervous system formed of three ganglia, supracesophageal, 

 thoracic and ventral (Nassonow, 1892 d, Xenos vesparum Rossi). 

 (See fig. 2, Nos. 14-17, p. 60.) 



14. Absence of Malpighian vessels and cutaneous glands in male 

 and female (Nassonow, 1892 d, Xenos vesparum Rossi). 



15. Presence of unpaired sexual canals on the second to fourth, 

 fifth, or sixth abdominal segments of the female, in the form of 

 curved tubes, resembling the segmental organs of annelids (Nasso- 

 now, 1892 d, Xenos vesparum Rossi, 1893 a, Stylops mellittse Nasso- 

 now not Kirby; Muir, 1906, Elenchus tenuicornis Muir not Kirby.) 



16. Absence of ovaries (Nassonow, 1892 d, Xenos vesparum Rossi). 

 The simultaneous development of all eggs (Brues, 1903, Xenos peckii 

 Brues not Kirby). 



17. The retention of the female in its unshed pupal skin (Meinert, 

 1896; Pierce, numerous species). 



18. Two pupal instars and the retention of the puparium and first 

 pupal skins by the second male pupa (Pierce, Acroschismus pallidus, 

 pecosensis) . 



19. The fusion of head and thoracic segments to form a cepha- 

 lo thorax in the adult female (Nassonow, 1892 d, Xenos vesparum 

 Rossi; Pierce, Acroschis7nus pallidus Brues). 



20. Larviparous reproduction. 



21. Hypermetamorphosis. 



22. Permanent parasitism of female. 



23. Fertilization probably by releasing spermozoa in the buccal 

 cavity or else in the opening of the brood canal. 



In rebuttal it may be advisable to show the fallacies of the classi- 

 fications which called the Strepsiptera coleopterous. 



Saunders (1872), following Schaum, and Lacordaire (1859) gave 

 the following as the principal reasons for ranking the Strepsiptera as 

 Stylopidse, coleopterous : 



