10 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.71 



Variation of this nature in Sphecids is common, and examples are 

 sometimes met with in which there is a petiolated cell on one side 

 while the other is perfect. An examination of about 1,100 specimens 

 of one species of SpTiex shows that venation variations are liable to 

 occur either on one or both sides in about one specimen of each hun- 

 dred, the variation occurring most frequently in the males. Miscus 

 arvensis Dahlbom is such a specimen. 



PsammopMla was established by Dahlbom for insects of this tribe 

 in which the petiole consists of only one segment. This name being 

 preoccupied, Podalonia takes its place. This will be discussed at 

 greater length later in this paper. Coloptera, proposed by Lepeletier 

 was based as follows: "Caracteres. Ceux des deux genres precedens" 

 (Ammopliila and Miscus) "sauf ce qui suit: Deux cellules cubitales 

 seulement." A careful study of the American species of Coloptera 

 reveals no characters separating this insect from Sphex, and the 

 unreliability of venation alone, used for this purpose has just been 

 indicated and will be further demonstrated in the course of this paper. 



Parapsammophila, created by Taschenberg, appears to be based 

 largely upon the presence of two teeth on each claw. As no Sphecini 

 with toothed claws have thus far been observed in North America, 

 the validity of this genus need not be considered further here. 

 Eremochares , established by Gribodo, has as its chief reason for exist- 

 ence, the presence of a single tooth on each claw. Ceratosphex has 

 its petiole of two segments and the claws are armed with two teeth. 

 As no species with these characters have been found in North Amer- 

 ica, this leaves Sphex (AmmopMla Authors) and Podalonia as the 

 two genera to be considered in this country. 



Whether these are sufficiently distinct to entitle them to be regarded 

 as different is an open question. Kohl^ regards them along with 

 Eremochares, Parapsammophila, Coloptera, etc., as "species groups." 

 They may be considered either as subgenera or genera according to 

 the ideal standards in the minds of different students of the group. 

 Species which might be termed typical in each group are easily 

 recognized and support the valuation of the groups as genera, but in 

 other cases it becomes somewhat difficult to draw the line between 

 them. My personal opinion is that, when a world study of these insects 

 has been made, these groups will be regarded as of at most only sub- 

 generic value. For the purpose of this paper, however, it is most con- 

 venient to treat them as genera and deal with Podalonia at this time, 

 leaving Sphex for separate consideration. 



ANALYTICAL KEY TO GENERA 



1. Petiole consisting of one segment, its dorsal plate quite broad and more or 

 less bell-shaped; comb teeth on hind tibial spine not crowded, rather stout; 



» Annalen des k. k. Naturhistorischen Hofmuseums, Wien, vol. 31, p. 228, 1906. 



