70 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
basally pointing V, and reaches to about the apical fifth of the lateral 
lobes; ventral surface of median lobe membranous. 
Female.—Dimensions 7.5 to 9.0 mm. by about 3.2mm. Very similar 
to male. Fully winged and capable of flight. Identification validated 
by pair taken mating. Sternites 2-6 dark brown except for light 
organ in median third or quarter of 6 (pl. 3, fig. 33) ;7 occasionally, and 
8 usually light brown; hind margins sinuate and sometimes very 
slightly notched in centers. Tergites all dark brown except for 7 and 
8, which may be lighter. Head width 1.16 mm. Eye length 0.6 mm. 
Frons width 0.50 mm. Tibal spurs same as in male. 
Type and paratypes —U.S.N.M. No. 57316. 
Distribution —Catherines Peak (type locality), July 28, 1941, type 
male and three male and three female paratypes; June 21, 1936, one 
female paratype; and July 27, 1936, one female paratype; Mossmans 
Peak, July 31, 1941, one male and two female paratypes. One of the 
few species in which more females than males were found. 
Named for my wife, Elisabeth Mast Buck, in appreciation of her 
constant and extensive assistance in the field and laboratory. 
Genus DIPHOTUS Barber 
The most conspicuous difference between Diphotus and Photinus is 
the restriction of the light organs, in both sexes of the former, to a pair 
of lateral spots in sternite 8, the usual position of the larval organs in 
most luminous lampyrids. These are usually small, as in D. masti 
(pl. 3, fig. 34), but occasionally, as in D. semifuscus Barber, they occupy 
nearly all the sternite. Other differences between Diphotus and 
Photinus are the presence, in the former, of pinkish or purplish color 
in some of the viscera, which may show externally through trans- 
lucent regions such as the pronotal disc and abdomen, the presence of 
relatively straight posterior margins on the abdominal sternites (pl. 3, 
fig. 34), and of relatively larger eyes. In place of the one or two rather 
conical spurs projecting from just behind the distal rim of the tibia in 
Photinus, Photuris, and Presbyolampis, diphotids have an even close- 
set circlet of more slender spurs projecting distally from the extreme 
distal rim of the tibia (pl. 2, fig. 17). Strictly speaking these are 
probably modified hairs, rather than derivatives of the type of spur 
found in Photinus, Photuris, and Presbyolampis. In forms where they 
are darker than the leg vestiture (e. g., D. montanus, mutschleri, semi- 
fuscus, bucki, and dahlgreni) they are easily distinguishable from 
ordinary hairs by their diameters and position, but in forms where 
both spines and hairs are light colored (e. g., D. ornicollis, darlingtont, 
and masti) the two are often difficult to distinguish from each other. 
As already mentioned Diphotus has simple tarsal claws (pl. 3, fig. 
29), although, as will be noted later, some species have an additional 
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