328 ENTOMOLOGICAL NEWS. [ July, 16 
would have unhesitatingly believed that they represented at 
least four genera.” 
The only single character which runs through the entire 
series is the absence of the internal soft fold. Probably the 
spines along the shaft are also a character of the entire group 
but they are so delicate that they have to be looked for spe- 
cially, and in laterale and adustum I did not notice their ab- 
sence until the drawings were assembled in the plate. An- 
other character which runs through the entire group, but 
which is not so obvious, because it appears in a different form 
in each species, is one or more outgrowths (septa, lobes, 
spines, hooks, etc.) which appear along the median line of 
the dorsal or internal surface of the distal lobe. Outgrowths 
along this line, though they do occur in a few other genera, 
are rare. The singular paired outgrowths of the lateral edges of 
the distal segment, as they are developed in temporale, apicale, 
gracile, ablutum, ascendens, kennedii, cuyabae, and truncatum, 
are unusual, though they also appear in other genera. The 
strangest and least comprehensible development in the entire 
series is that of the pair of heavily chitinized hooks on the 
apex of the distal segment in apicale (Plate XVIII, fig. 3). 
A strong chitinization at this point is all but unique among the 
more than five hundred species of Zygoptera examined. The 
terminal soft fold varies in development in this series but I 
should hesitate to say that it was entirely absent in those 
species in which it is not figured, as it is at times gossamer- 
like and, if the specimen is the least dry clings so closely to the 
terminal segment that the most careful dissection may fail to 
loosen it. However I can state that it is as a rule poorly de- 
veloped except in cheliferum, (Pl. XVIII, fig. 26). 
The following brief notes are to amplify the characters 
shown in the figures on Plate XVIII. 
Acanthagrion ablutum Calvert, figs. 10-11. The edges of segment 3, 
twisted at its base and turned in, form a pair of “shelves” between 
which is an ill-defined median septum. 
°Prof. O. A. Johannsen has just called my attention to a condition 
similar to this in certain genera of Mycetophilidae. In some genera 
in this family the hypopygium in the male varies between species so 
much that the parts cannot be homologized. 
