CLASS II. MYRIAPODA: ORDER 2. CHILOPOLA. 
599 
double thread; the circulation is effected by a long, cylindrical, dorsal vessel. The species 
are all unisexual. In some kinds the young, on first escaping from the egg, possess nearly ai] 
the characters of their parents, although the number of segments and limbs is always less, and 
increases at each change of skin ; but some, as the luli^ undergo a sort of metamorphosis, coming 
from the egg either quite destitute of feet, or furnished with only three pairs of these organs, 
and it is not until after several moultings that they attain the same number of legs as their 
parents. This metamorphosis, such as it is, indicates the close aUiance of these creatures with 
the insects ; and many authors either include them in the class Insecta or retain them in a sepa- 
rate class. The Myriapoda form two orders, the Chilof/natha and the Chilopoda ; of the former 
there are over seventy species ; of the latter about one hundred. 
ORDER 1. CHILOGNATHA. 
In these the body is generally of a convex form, composed of numerous homy arches, below 
which an immense multitude of little feet may be seen, whence the name of Millepedes^ or Thou- 
sand-legs, by which these animals are commonly known, is derived. Each segment of the bodv 
bears two pairs of limbs, with the exception of the hindmost segment, which is destitute of such 
organs. The antennae are short, and composed only of seven joints, and the jaws are reduced to 
a rudimentary condition. The species are found to feed principally upon vegetable matters, 
generally when in a state of decay. Their movements, notwithstanding their immense number 
of legs, are always very slow, and they generally endeavor to escape danger by rolling themselves 
up into a ball. There are several families belonging to this group, but the best-known species is 
the Gally-AVorm, lulus terrestris, often found, like the rest of the tribe, in damp moss, and 
sometimes crawling over the trunks of trees. The /. maximus of Brazil is often seven inches 
long. The Glomeridce, belonging to this order, resemble wood-lice. 
THE ELECTKIC SCOLOPBNDRA. 
ORDER 2. CHILOPODA. 
These animals are usually of a flattened form, and live in the earth or under stones. They 
run with considerable swiftness in pursuit of their prey, and can even progress backward by the 
assistance of their tail-like hind-legs, which at other times are dragged helplessly behind them. 
Their food consists of insects, which they seize with the powerful jaw-like organs attached to 
the lower lip. There are various kinds, but the most remarkable family is that of the Scolopen- 
dridce, commonly called Centipedes : they are nocturnal in their habits, prey on insects, and are 
active and voracious creatures. Some of these, in tropical climates — as for instance the Malfai- 
sante, a West Indian Scolopendra — grow to the length of six inches, and certain writers say 
to twice that size. Their bite is very painful, and sometimes fatal. The smaller and harmless 
species, common among us, are found at night concealed under timber or in holes in walls. 
The Electric Scolopendra, S. electrica, is a European species, luminous in the dark. 
Tlie Geophilidce have almost thread-like bodies, some species of which are phosphorescent. 
The species of Scutigera have the body divided into fifteen segments, each bearing eight 
pairs of long multi-articulated legs ; they are very active, and often lose some of their legs when 
touched. Those of the genus Litkobius have the body above and below divided into the same 
number of segments, each of which bears a pair of legs. 
