x 54 Yorkshire Ptychoptera, including P. longicauda. 
at times, with the meta-tarsal colour character, and found 
the venation, which he does not use, very helpful ; here the 
species fall into three groups : — 
I. Where Rs (the common base of Wingate’s V2 and V3) 
is Ion g—contaminata L. 
II. Rs medium length = albimana F., scutcllaris Mg., 
minuta Tonn. 
III. Rs short = lacustris Mg., paludosa Mg., longicauda 
Tonn. 
The spotted wings differentiate albimana from scutellaris 
and minuta, and these two last are identified by the appear- 
ance of the (J genetalia as seen from above ; in scutellaris 
the anal opening is visible above as VII., but is not so in 
minuta VI. Again, the difference of this part of the insect 
will divide longicauda (see IV.) from lacustris (see V.). 
It appears impossible to decide the species of many $ 
specimens, for instance, the all black abdomen character of 
paludosa is only reliable in the case of <Js, many of my 
$ lacustris lack the yellow bands, and are only placed under 
the name because they were captured with of this species. 
Figs. I., II. and III. were drawn from the wings of P. 
contaminata L., P. albimana F., and P. lacustris Mg. re- 
spectively, and IV., V., VI., VII. are diagrammatic, and 
adapted from Tonnoir’s illustrations. 
Naturalist 
