310 PROCEEDINGS OF THE NATIONAL MUSEUM. 



21. Without golden thoracic pubescence 22. 



With golden thoracic pubescence Isaduntia coalipennis (Spinola) (p. 351). 



22. First segment of antennal filament longer than fifth or sixth. 23. 



First segment of antennal filament shorter than fifth or sixth 24. 



23. 3Iedian segment without long white hairs above. 



Isodo)ilia aztecion, female, (Saussure)(p. 353). 

 Median segment with many long white hairs above. 



Isodontiaaztevitm civereu))), female, (H. Fernald) (p. 356). 



24. Body hairs gray 25. 



Body, hairs bhick Isodontla a -tecum var., male, (Saussure) (p. 356). 



25. Front part of wings fuliginous Isodontla aztecum, male, (Saussure) (p. 354). 



Wings entirely fuliginous Isodontia aztecum var., male, (Saussure) (p. 356). 



26. Wings dark fuliginous Isodontia e.rornatum ( H. Fernald ) ( p. 350). 



Wings yellowish: at most only somewhat fuliginous. 



Isodontia costipennis (Spinola) (p. 351). 



27. Legs black Isodontia luirrisi H. Fernald ( p. 359 ) . 



Legs more or less yellowish 28. 



28. Abdomen black Isodontia auripes H. Fernald ( p. 356). 



Abdomen more or less yellowish Isodontia elegans (Smith) (p. 361). 



29. Females 30. 



INIales 49. 



30. Hind tibi;e suddenly thickened at the end on the inner side. 



Proterosphex cubensis H. Fernald (p. 367). 

 Hind tibi;e not suddenly thickened 31. 



31. Abdomen more or less red or reddish yellow 32 



Abdomen black (one exception) 40 



32. Legs black 33 



Legs more or less red or rusty yellow 34 



33. Abdomen partly black; pubescence pale straw to silvery white. 



Proterosphex te.ranum (Cresson)(p. 414). 

 Abdomen entirely reddish ; pubescence golden yellow. 



Proterospjhex lautum (Cres8on){p. 371). 



34. Anal segment red; some of the abdominal segments black. 



Proterosphex dubitatum (Cresson)(p. 394). 



Anal segment red or black; when red the other abdominal segments are also 



red _ 35. 



35. None of the abdominal segments black 36. 



Hinder abdominal segments black; petiole black 39. 



36. Petiole black Proteroxphex resinipes H. Fernald (p. 386). 



Petiole red, orange, or yellow 37. 



37. Hairs on dorsum of median segment gray. 



Proterosphex ashrneadi, new species (p. 389). 

 Hairs on dorsum of median segment not gray 38. 



38. Wings hyaline, with a yellow tinge. 



Protcrospliex icJineumoneum aurifluun) (Perty)(p. 403). 

 Wings more or less fuliginous. 



Proterosphex ichneumoneum fulvirentris (Guerin)(p. 403). 



39. Femora red (rarely black near base); a pubescent band along the stigmatal 



groove Proterosphex ichneumoneum (Linnaeus) (p. 399). 



Femora black (sometimes red at tip); no pubescent band along the stigmatal 

 groove Proterosphex viaximiliani ( Kohl ) (p. 397 ) . 



40. Legs partly rust red or rust yellow 41. 



Legs black 46. 



