Fi Det Le 
ments, inner on middle 
on the next, and outer on the third; 
being one, 
but a portion of the inner remains inner 
throughout. 
Digestive system. 
are 4 mm. long, flat and simple, bent 
abruptly outward beyond the middle, 
tapering slightly and regularly to a 
bluntly rounded tip. 
The malpighian vessels originate in 
The salivary glands 
“ @D 
an oval gland or sac, 0.45 mm. long and 
0.2 mm. broad, a short distance beyond 
which the under branch is thrown off and 
immediately afterward the two others. 
The under branch 
a straight and not a tortuous course, and 
is proportionally about as long as in 
Danais; the upper branch extends for- 
ward for a distance of 3.75 mm.; the 
lateral to the point where the silk vessels 
bend, 7 mm. from its origin. 
Nervous system. The cephalic lobes 
are globular. The cords connecting the 
second and third body-ganglia run to- 
gether for nearly one-quarter the distance 
from the second backward, then diverge 
considerably, and again converging, enter 
the third ganglion ata perceptible distance 
apart; nearly the same is repeated be- 
tween the first and second ganglia, but 
passes forward in 
309 
they diverge nearly from their origin ; 
between the first body-ganglion and the 
suboesophageal ganglion the cords are par- 
allel, but separate, and a little parted in 
the middle. The third ganglion lies in the 
middle of its segment, the fourth at the 
anterior edge of its segment, and only 
0.75 mm. from the third ; the fifth in the 
middle of the anterior half of its seg- 
ment; the eleventh ganglion is consider- 
ably longer than broad, and the pair of 
posterior, backwardly directed, diverging 
nerves is larger than any of the others, 
and may be looked upon as the continua- 
tion of the connecting cords between the 
other ganglia. 
Glandular system. The basal thread 
of the silk vessels is straight and not 
tortuous; the basal half of the stouter 
vessel is flattened; it extends backward 
as far as the third abdominal segment 
and then turns abruptly, with a slight 
forward curve, to the upper side of the 
body, where it continues in a straight 
line as far, apparently, as the end of the 
sixth abdominal segment. The length 
of the initial thread or duct is 3.25 mm. ; 
of the portion of the ribbon or vessel upon 
the under surface 4 mm.; of that upon 
the upper surface 5.25 mm. 
(To be continued on p. 319-) 
COLOR OF THE LIGHT EMITTED BY INSECTS. 
BY HENRY WARD TURNER, ITHACA, N.Y. 
Some specimens of Pyrophorus nocti- 
lucus Linn., from the West Indies, that 
were brought to the Academy of natural 
sciences, at Philadelphia, gave out a very 
bright-green light from the two dorsal 
prothoracic spots, and also from the 
ventral surface near the base of the ab- 
domen. Gosse (Ann. and mag. nat. 
hist., 1848, s. 2, v. 1, p. 200) says they 
give out a rich yellow-green light when 
flying and a green light when in captivity. 
Photuris pensylvanica gives out (some- 
times at least) a very decided green light, 
and Photinus pyralis a yellow light from 
the ventral surface of the two or three 
last segments of the abdomen. 
