60 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, 97 
samples is of vital importance in obtaining specimens suitable for 
adequate study. All the descriptions presented below, except that 
of Diphotus darlingtoni, are based on specimens prepared by the 
following technique, which produces samples far superior to ordinary 
pinned material in cleanness, flexibility, and preservation of natural 
form and color: Place the specimen alive in at least 10 volumes of 
70 percent alcohol and leave for several days or longer; extend the 
abdomen and hook out the aedeagus with a bent-tipped micropin so 
that both surfaces are fully displayed (if it becomes detached, cement 
on a hair and mount with the specimen); place in 95 percent alcohol, 
one hour; absolute alcohol (2 changes), overnight to several days; 
benzene, 10 minutes; allow to dry on porous tile or filter paper; mount 
on point with cellulose acetate cement diluted with amyl acetate. 
The male has been used as the basis of classification since males are 
almost always very much more abundant in collections than females 
(perhaps because it is usually only the male that flies and flashes 
spontaneously), and because when several species are active at the 
same time and place, females cannot always be associated with males 
of the same species. Following Barber (1941) particular weight has 
been given to the morphology of the male copulatory apparatus 
(aedeagus). In most cases this evidence merely confirms conclusions 
that are indicated by habitus and other morphological evidence, but 
occasionally it is particularly valuable in suggesting affinities not 
otherwise obvious and, conversely, in separating forms superficially 
very similar. However, a statistical analysis of aedeagal dimensions 
in populations of four “subspecies” of Photinus evanescens Barber 
(Buck, 1942) shows that the aedeagus is no less variable in form than 
most other structures and indicates that too much importance should 
not be attached to minor variations in contour. 
In most instances I have followed the terminology of Torre-Bueno 
(1937). For the aedeagus I use, like Barber (1941), the standard 
notation of Sharp and Muir (1912), as follows (usmg Photinus lewisi, 
pl. 2, fig. 11, as an example): The aedeagus consists of two lateral 
lobes (LL), which lie on each side of and may partly enclose the single 
median lobe (ML). The lateral lobes are typically heavily sclerotized, 
except perhaps at their extreme tips, and are rigid, though jomted at 
their basal ends (anteriorly) and movable in life by means of complex 
muscles within the basal piece (B) of the aedeagus. The lateral lobes 
accordingly may be found spread apart laterally to different degrees 
in different specimens. The median lobe is usually sclerotized dorsally 
and laterally, membranous ventrally. The function of the lateral lobes 
is thought to be to spread the female aperture and guide into it the 
tubelike internal sac (pl. 2, fig. 12a, IS), which during mating emerges 
from the tip of the median lobe. Actually, the internal sac is rarely 
