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[December 
structure. The small basal ring and form of the aedoeagus and 
volsellar structures are all suggestive of the Bethylidae; however, 
there is no clear separation of the parameres from their basal plates, 
a feature more characteristic of the Scolioidea and certain Formi- 
cidae. All of this is of some academic interest, but at the same time 
one is left with the feeling that although the terminalia of Plumarius 
do not quite resemble those of known Bethyloidea, Scolioidea, or 
Formicoidea, in fact there seem to be no well defined superfamilial 
characters in the genitalia. One can at least say that there are no 
noteworthy reductions or specializations in the terminalia of Pluma- 
rius. 
The systematic position of the Plumariidae. — It is sometimes 
stated that the major feature of the Bethyloidea is the lack of sexual 
dimorphism in antennal segmentation. If this is true, these wasps 
belong in the Bethyloidea. Other bethyloid features include the 
head shape of the female, segmentation of the labial palpi, lack of 
constriction between the first two metasomal segments, and the 
genitalic features mentioned above. However, the broad, well-veined 
hind wings, with distinct closed cells, tend to eliminate the group 
from the Bethyloidea, as do the spinose front and hind legs. The 
Bethyloidea must, of course, have evolved from an ancestor having 
a more complete venation, just as the Scolioidea undoubtedly evolved 
from an ancestor lacking sexual dimorphism in the antennae. I 
suggest that Plumarius is a relic of an ancient stock, one portion of 
which gave rise to the Bethyloidea, another to the Scolioidea and 
higher wasps. This ancient stock has apparently managed to sur- 
vive by becoming adapted to severe desert conditions in South Amer- 
ica and South Africa, the males being nocturnal, the females 
hypogaeic. 
It should be noted that Sharov (1957) has described and figured 
the wing of a supposed wasp from the Cretaceous of Siberia, Creta- 
vus sibiricus (Fig. 10), pointing out the resemblance of the wing 
to that of Plumarius (Fig. 9). Although some differences are ob- 
vious, particularly in the shape of the stigma and marginal cell, there 
are indeed some striking similarities, particularly in the presence of 
several more or less distinct veins on the outer third of the mem- 
brane which are absent in other wasps. Sharov interprets these as 
the termini of branches of the radial sector and of media. Bradley 
(1921b), however, notes the presence of “accessory spurs” in this 
position in many Mutillidae, and suggests that in Plumarius these 
veins arose from such spurs. 
