Be, Rea te 
20 BULLETIN BROOKLYN ENTOM. SOC. VOL. VII. June 1884. ] 
The hinds wings are furnished on the anterior margin, near the base 
with an organ, called the frenulum. 
In the male, it fits in a membrane, projecting from near the costa, 
on the under side of the fore wing, underneath which, longitudinially, — it 
moves freely. This however, is nearly, or quite obsolete in the female, 
and in my observation does not cover the projections of the organ. 
It has been thought to serve the purpose of holdirig the wings to— 
gether in flight; this end may be served; but in view of the modiiication 
of the organ in the female, it is more likely an instrument more particu- 
larly to keep the hind wing from getting above the fore wing. The 
frenulum in the male is a strong corneous spine. In the female, there 
are with but one exception in my observation. three spines, much slighter 
and weaker than in the male. I was much surprised to find how incorrect 
an idea existed among entomologists concerning this organ of the female 
of the Cafocale. Mr. Strecker in his catalogue of the Butterflies and 
Moths of N. A-. 1878. p. 34, speaking of the frenulum of Cavocala says 
“simple in male, and forked or double in female.” Mr. Grote, in the 
years gone by, sneered at another, who was in doubt as to the sex of a 
Catocala whose abdomen was wanting, saying in effect, that any one who 
had the least knowledge of the anatomy of the Voc/uidae, would know 
that the frenulum was bifid in the female. And so late as August 1883, 
(Proc. Amer. Phil. Soc. XXI, pp. 135—36), he says of the No:tudae, 
‘they have a simple frenulum, which is divided, (not ‘double’) in the 
female.” The facts are, so far as the Ca/ocalae are concerned, the frenu— 
lum is simple and single in the male, but in the female it is not forked, 
divided, double, or bifid, but the only proper way to express it is that 
there are in the female three frenula;—for the spine is the frenulum, and 
there are three of these. There is an adaption of the wing to receive the 
spine; but the name must attach to the spine, and not to a section of 
the wing itself. | 
I found one Q gracis with four frenula, but this is the only in- 
stance of hundreds examined, that I have found among the Cafoci/le. 1 
have never seen one with two only. These frenula can not, it seems to 
me, be looked upon as specialized nervules, as in the female each one is 
set in a sort of a socket, and in no case is the organ a continuation of 
any nerve in the wing itself, 
Of the frenula of the Cavocalae females, the basal one is generally the 
shortest and most erect; the two others are of nearly the same length, 
