586 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.40. 



Whether such groups should be considered as genera or not is a 

 matter of opinion. For the present it may be well to recognize 

 them as such. 



Genus SOLIERELLA Spinola. 



As far as known to the author this group divides itself into two, as 

 follows : 



Emargination of the mandibles strong; transverse median and basal vein interstitial 



or nearly Solierella Spinola. 



Emargination of the mandibles weak; transverse median basad of basal vein. 



Niteliopsis S. Saunders. 



Kohl's group 3, 1 which is Niteliopsis, is not correctly defined 

 according to Saunder's description. Kohl says, "Die Basalader 

 entspringt interstitial." Saunder's figure shows it quite free and 

 basad of the basal vein. The mandibles are originally described 

 thus: "Mandibulae curvatse, basi robustse prope medium excavatae, 

 apice acutae edentulse." 



Genus SILAON Pieeioli. 



Sylaon is an emendation. All the American species referred to 

 Niteliopsis belong here. The species known to the author may be 

 divided into the following groups : 



Transverse median basad of basal vein; first cubital cell receiving a recurrent vein. 



group compeditus Pieeioli. 

 Transverse median beyond basal vein; second cubital cell receiving both recurrent 

 veins or the first recurrent interstitial with the first transverse cubitus. 



group vierecki Rohwer. 



Transverse median and basal veins interstitial or nearly so 1. 



1. First recurrent vein received by the first cubital cell group chilcnsis Kohl. 



First recurrent vein received in the second cubital cell or interstitial with the first 

 transverse cubitus group plenoculoides Fox. 



The Nearctic species would be grouped as follows, according to the 

 above arrangement: 



Group compeditus. 

 sayi (Rohwer). 



Group chilensis. 

 lucidus (Rohwer). 

 parvus (Rohwer). 

 niger (Rohwer). 

 affinis (Rohwer). 

 inerme (Cresson). 

 mexicanus (Rohwer). 



Group vierecki. 

 vierecki (Rohwer). 

 fossor (Rohwer). 

 foxii (Viereck) from description. 



Group plenoculoides. 

 plenoculoides (Fox). 

 striatipes (Ashmead) (male, not fe- 

 male). 

 modestus (Rohwer). 



' Die Gattungen der Sphegiden, 1S9C, p. 453. 



