overlaps the greater number of the pieces 
belonging to the mouth. The second segment, 
by far the larger and the stronger of the two, 
envelope, the strongest segment of the whole 
body, is entirely devoted to the support and 
movement of a pair of sharp bi-articulate and 
hooked fangs resembling jaws, that move trans- 
versely like the (so-called) mandibles of a 
_ Spider, but which are in reality only modifica- 
tions of the ambulatory feet converted into 
‘instruments for killing prey, each being per- 
_forated near its sharp termination with a long 
oval slit, through which venom is said to be 
instilled into the wound inflicted by this 
rmidable weapon. 
| ___ The head properly so called, namely the 
ular shield-like plate seen upon the dorsal 
irface at the anterior extremity of the body, 
although apparently consisting of a simple 
horny disc, is doubtless composed of several 
nents conjoined superiorly ; indeed, these are 
pletely confused, and inferiorly are too soft 
membranous to be distinguished, except 
the presence of those articulated appendages, 
hich, although forming parts of the mouth, 
still merely repetitions of the jointed legs 
ed to the other segments of the~ body. 
the most superficial plate, with its articu- 
appendage, the /abium and labial palpus of 
mologists, is but an incomplete ventral 
um, with its articulated limb in a rudimen- 
condition’ as compared with those of the 
dy, and is even armed with a distinct claw, 
e the locomotive legs. In like manner the 
nd pair, the mazille of authors, are legs 
one step further removed from their normal 
n, but not more so than are the poison- 
s already described. In the third pair or 
dibles we have a leg reduced to its terminal 
» and that is broad and serrated so as to 
ome useful in manducation. Lastly, the 
corneous and serrated piece (the Jabrum_) seems 
to be the last vestige left of limbs of this 
€scription, the two horny remnants of legs 
ing become consojidated with each other 
with the dorsal head-plate, so as to form 
anterior boundary of the mouth. 
imentary canal.—The alimentary canal in 
the Myriapoda is of extremely simple con- 
ion, and both in its form and general 
ngement, very nearly resembles that of the 
2 of Lepidopterous Insects. In Julus ter- 
is (fig. 311) the esophagus (h) is seen to 
f considerable capacity, in accordance with 
ature of the coarse food upon which these 
etable-eating species live. The stomach is 
and bowel-like, extending from the termi- 
of the esophagus to the insertion of the 
ic vessels. To this succeeds a wide and 
lated colon, which passes directly to the 
Aap of the body, where it terminates. 
the Scolopendroid genera the same con- 
rmation of the alimentary apparatus is met 
th, the stomach and intestine passing straight 
om the mouth to the anus without any pecu- 
Harities of structure worthy of notice. 
In Lithobius forficatus, which we may take 
asa Speciinen of one of the Chilopod Myria- 
MYRIAPODA. 
and, in fact, from the density of its corneous — 
549 
poda, a very similar arrangement exists; the 
Fig. 311. esophagus, which is pro- 
portionately narrow, ends 
in a_ simple stomachal 
enlargement of an oblong 
“shape, and this termi- 
nates in a straight bowel, 
the point of separation be- 
tween the one and the 
other being only indicated 
by the entrance of the 
biliary vessels. 
The glands connected 
with the alimentary ap- 
paratus closely resemble 
those of the insect larva. 
Two convoluted salivary 
tubes are seen folded up 
at the sides of the cso- 
phagus, where their con- 
volutions are intervolved 
into a species of ravel 
(fig. 311, i) with the 
origins of the hepatic ves- 
sels (4), which latter, after 
a tortuous course, are in- 
serted, as in Insects, at 
the termination of the sto- 
machal portion of the di- 
gestive tube. 
Respiratory System.— 
The Mirdanets respire in 
the same manner as In- 
sects by means of late- 
ral spiracles and tracheal 
tubes. The spiracular ori- 
fices are, in the Scolo- 
pendride, very conspi- 
cuous, as, for example, 
in Lithobius, (fig. 312,) 
where the corneous lips 
of the apertures leading 
to the trachee (s, s, s, s) 
are seen situated behind 
the origins of the legs, 
upon the sides of the 2d, 
4th, 6th, 9th, 11th, 13th, 
and 15th segments, occur- 
ring upon the alternate 
segments, except in the 
case of the 8th, where 
there is one missed. The 
trachez derived from these 
spiracles pass inwards to 
be disbributed upon all 
the viscera, ramifying in 
every partof the body, 
and thus conveying air 
throughout the system. In 
structure these air-vessels exactly resemble those 
of true Insects, and are equally characterized by 
the existence of a spiral fibre in their interior, 
whereby they are always kept permeable. , 
Circulatory system.—In the nature of their 
circulatory apparatus the Myriapoda are closely 
related to the Insects properly so called. A 
long dorsal vessel passes from the tail towards 
the head along the mesial line of the body. 
The sides of this vessel, on clearing away the 
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