ARTICULATA. 145 
Latreille in 1796, and considered a tribe of his order Gymnognatha by 
Burmeister, the body is apterous, more or less cylindrical, and often covered 
with minute scales like a silvery dust. The antennze are longer than the 
head, and the mouth is provided with mandibles and maxille. They are of 
active habits, living in woods, among moss, or beneath gtones and bark. 
Some of the small species are sometimes found on the surface of the water 
near the margin, or hopping about on the surface of snow in winter, some- 
times in great numbers. The order contains the two families, Podurida 
and Lepismide. 
Fam.1 Poduride. Here the body is oblong or globular, the antennee 
are rarely composed of more than four articulations, but in the genus 
Macrotoma the three or four articulations are divided into a great many 
rings or indistinct segments, indicating an affinity with the Lepismide. 
The palpi are indistinct according to some authors, and absent according to 
others. The mandibles and maxille are membranaceous, the eyes simple, 
varying in number, and the abdomen is four or six articulate. The pro- 
thorax is sometimes much reduced in size, or wanting above, although a 
part of it remains below, to which the anterior feet are attached. The 
posterior extremity is provided with a spring or appendage bent along the 
abdomen, and used in leaping. This, however, is wanting in the genus 
Anura, in which the mandibles and maxille seem to be absent. They 
are usually confined to damp places, and die very soon if deprived of 
moisture. The oral aperture is so minute that it is supposed they subsist 
upon the juices of decaying vegetable matter. 
Podura (pl. TT, fig. 79 a, natural size; 6, magnified, exhibiting the 
caudal spring). Smynthurus (fig. 80) has the abdomen large and globular. 
The species of this genus are often seen hopping upon the surface of water 
and snow. The dark-colored species of this family are so abundant at 
times as to give the snow the appearance of being sprinkled with course 
gunpowder. J. M. M‘Minn mentions their occurrence in the mountains of 
Pennsylvania, in the following words (Proceed. Acad. Nat. Sci. iv. 246) : 
“T have frequently noticed them in mid-winter on the snow, but I never 
saw such a multitude of them together as I witnessed on the 17th of 
Feb., 1849. The snow was entirely covered for the fourth of a mile along 
the road, and several rods on either side. The mercury in Fahrenheit was 
standing about fifteen degrees; the atmosphere was dry and clear. These 
little animals were quite stupid, and to all appearance had been but a short 
time there, and as it was about nine o’clock in the morning, I judged that 
they arrived at night. Their motion was slow, and those on the top were 
quietly endeavoring to get under. The next day, when I again passed the 
spot, I could not detect a vestige of them. The wind had been strong from 
the north for several days, and I have noticed that we had strong north 
winds whenever I had seen them.” This species is probably the Podura 
muvicola described by Dr. A. Fitch, who gives a similar history of it in his 
account of the ‘‘ Winter Insects of Eastern New York,” published in the 
Am. Jour. of Agr. and Sci. for May, 1847. 
fam. 2. Lepismide. In this family the antenne are setaceous, and 
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