25 
(as Staudinger and Meyrick have done) until it has been more closely 
studied. In our British representatives of “Acidalia ” there occur four 
.varieties of hindleg structure :— 
(a) Both sexes with two spurs. 
(b) Male spurless, female two-spurred. 
(c) Male spurless, female four-spurred. 
(d) Male two-spurred, female four-spurred. 
More neatly analysed, this shows that the female may have either 
two spurs or four, and that with either of these types of female, there 
may belong a male which is spurless, or one which is two-spurred. 
Herrich-Schaeffer, whom Meyrick has followed, though he employs 
different names, recognised all these four as genera. Group a, is 
Acidalia, H.-S . = Sterrha, Meyr.; b, is Ptychopoda, H.-S. = Eois, Meyr.; 
c, is Arrhostia, H.-S . = Leptomeris, Meyr.; and d, is Pylarge, H.-S., Meyr. 
But the evidence which is derivable from other sources, such as 
larva, venation, genitalia, geographical variation, and even superficial 
suggestions of affinity, shows that it is here the. female armature which 
is chiefly significant, and it is a question whether we are yet in a 
position to affirm more than two genera. One of them will probably 
require breaking up, but it may be on other characters ; the other is 
remarkably homogeneous. In order to show the present state of our 
knowledge, and the difficulty of accepting too implicitly the genera 
founded on the $ armature, it will be necessary to go into a little 
detail. 
I shall call the two main groups, which are undoubted genera, by 
the names Ptychopoda and Acidalia. There are probably older 
names than both these, but they happen to apply to outlying species 
which might conceivably form separate genera—and which, indeed, 
do form such in the estimation of some systematists—it would seem a 
little too previous to substitute them for better-known group names. 
To be sure, Ptychopoda may not be very familiar to most of my hearers, 
though it is the creation of one of our British pioneers, Stephens, and 
is maintained in his British Museum List in 1850; but it is also used 
by Herrich-Schaeft’er and von Heinemann, and by Warren in the mass 
of descriptive work which he published in the Novitates Zoologicae. 
In order to facilitate future reference, and the adoption of the right 
names when the extent of the genera has been decided upon, I quote, 
with their type species, all the older names concerned. 
1802.— Scopula, Schrank, Fauna Boica, ii. (2), 162. Type, ornata, 
Scop, (vide Entom., xxxix., 266). 
1825.— Acidalia, Treitschke, Schmett. Ear., v. (2), 438. Type, 
virgulata, Schiff. = strigaria, Hub. (vide Entom., xlii., 3). 
1825.— Idaea, Treitschke, Schmett. Eur. v. (2), 446. Type, lineata, 
Scop .—dealbata, Linn, (vide Stephens, Cat. Brit. Ins., ii., 136, 
1829).* 
* Mentioned here because it obtained some currency as an Aeidaliid genus, and 
was resuscitated in that state by Moore [Ley. Ceyl., iii., 452, with type, aversata, 
Linn.), and one or two others who considered Acidalia preoccupied. 
XX. 
