404 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.59. 



Key to tribes of subfamily Nyssoninae. 



1. Mesopleura without a dorsal plate; propodeum with its dorsal angles dentate; 



second cubital cell petiolate (or rarely wanting by absence of first intercubitus) ; 



stigma small Nyssonini. 



Mesopleura with a dorsal plate (poorly denned in Ammatomus and present only 

 posteriorly in Sphecius); dorsal angles of propodeum not dentate 2 . 



2. Pronotum long, subequal in length with the scutellum; suture between the meso- 



and meta-pleura angulate so the metapleura is wider above; second cubital cell 



periolate; stigma large Alysonini. 



Pronotum short, normal; suture between the meso- and mata-pleura straight so 

 that part of the metapleura is nearly parallel sided ; second cubital cell sessile. .3. 



3. Stigma very small; no suture from below tegula to prepectus; sternauli want- 



ing Spheciini. 



Stigma large, well developed 4. 



4. Sternauli well defined Hoplisini. 



Sternauli wanting Gorytini. 



Tribe NYSSONINI. 

 Genus NYSSON Latreille. 

 For the time being, and until the species from other regions can 

 be studied, it seems best to consider the various North American 

 groups of Nyssonini as subgenera. That this will be the final or more 

 logical arrangement is, however, to be doubted, because the differ- 

 ences between Zanysson and Nysson are of greater importance than 

 the differences between Nysson and Brachystegus. The subgenus 

 Foxia is also distinctly limited and may be a genus. 



Key to the North American Subgenera of Nysson. 



1. Metanotum bilobed ; hind tibiae serrate on their outer margin; cubitella arising 



well beyond end of anallen cell; apical tergite of male usually with four or more 



teeth Zanysson, new subgenus. 



Metanotum not bilobed 2. 



2. Hind tibiae serrate on their outer margins; first intercubitus wanting; both recur- 



rents joining the first cubical cell Metanysson Ashmead. 



Hind tibiae not serrate on their outer margins, at most spinose 3. 



3. Second recurrent joining the third cubital cell; sides of apical tergites armed with 



spinelike protuberances; cubitella arising well beyond the end of anallen 



cell Foxia Ashmead. 



Both recurrents joining the second cubital cell; apical tergites without spinelike 

 protuberances 4. 



4. Cubitella arising before or nearly interstitial with nervellus Nysson Latreille. 



Cubitella arising far beyond nervellus 5. 



5. Third intercubitus present Brachystegus A. Costa. 



Third intercubitus wanting Hyponysson Cresson. 



Zanysson, new subgenus. 

 Paranysson Cresson, Trans. Amer. Ent. Soc, vol. 9, 1882, p. 273. — Ashmead, 

 Can. Ent., vol. 31, 1899, p. 326 (not Guerin 1844 or Turner 1914). 



Genotype. — Nysson texanus Cresson. 



According to Turner 2 both Cresson and Ashmead were wrong in 

 placing the North American species of Nysson which have the meta- 



1 Ann. Mag. Nat. Hist., ser. 8, vol. 14, 1914, p. 338. 



