84 
Psyche 
[September 
genitalia when doing taxonomic work on the Mymeleonti- 
dae. The writer has found that the structure of the gon- 
arcus, and especially of the parameres, furnishes most use- 
ful characters; accordingly these are illustrated for all the 
species treated below, when male material was available. 
Within a species, there seems to be little variation in their 
size and structure; unfortunately, it will sometimes be 
found that closely related species have almost identical in- 
ternal genitalia. Tjeder’s terminology 3 is used. 
Dorsally, there is present an arched sclerite, the gonar- 
cus, which bears at its apex a small hood-like structure, the 
mediuncus. Loosely articulated with the mediuncus are the 
parameres, which often are produced to form hooks. Or- 
dinarily, these structures will be found to lie in a pouch 
between the bases of the ectoprocts (“male appendages”) ; 
occasionally, this pouch will be found everted (Figure 32). 
The genital opening is on the ventral side of this sac, its 
position being marked by a small sclerite (Figure 32, dotted 
lines). As eversion takes place, the spatial relationships 
of the sclerites change markedly. In some species (e. g. 
Hesperoleon and relatives) the parameres have a thin re- 
gion near their middle, the hinge, where they may fold when 
the genital sac is inverted. Upon eversion, they straighten 
out, and the points of the hooks become more divergent. 
The reader is cautioned that, because of this folding, it 
was not possible to draw all the figures from the same view- 
point, and that, as a result, several of the figures are dis- 
torted. The side view gives a much better impression of the 
shape of the parameres than does the rear view, for this 
reason. In Eremoleon the parts are fairly rigid. 
For critical examination, it is necessary to remove the 
gonarcus and parameres from the abdomen; these can 
easily be teased out after boiling the tip of the abdomen in 
KOH. The genitalia are stored in glass vials containing 
glycerine, pinned beneath the specimen. If the corks are 
boiled in paraffine, there is less danger of the glycerine 
soaking through to corrode the pin. This can also be mini- 
mized by piercing the cork at a 45 degree angle, so that 
3 Tjeder, Bo, 1954, Ent. Medd. 27:23-40. 
