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cast naked upon the. earth, without limbs, 
exposed to every injury, but frequently 
armed with a poison the most deadly and 
horrible, which is contained in tubular fangs 
resembling teeth, placed without the upper 
jaw, protruded or retracted at pleasure, and 
surrounded with a glandular vesicle, by which 
this fatal fluid is secreted. (See Poisons.) 
But lest this tribe should too much encroach 
upon the limits of other animals, the benevo- 
lent Author of Nature has armed only about a 
tilth in this dreadful manner. ' The jaws are 
dilatable and not articulate, and the oesopha- 
gus so lax, that they can swallow without 
mastication, an animal twice or thrice as 
large as the neck. There are seven genera, j 
viz, the 
Achrochordus Coecilia 
Amphisbsna Coluber 
Anguis Crotalus. 
Boa 
The distinction of species in this numerous 
tribe is often peculiarly difficult. Li mix us 
persuaded himself that an infallible criterion 
might be found in the number of scaly plates 
on the abdomen and beneath the tail ; and 
accordingly attempted in the -Systems Natu- 
rx io discriminate the species, by this mark 
alone. Experience, however, has sufficiently 
shown that, though often highly useful in the 
investigation of these animals, it is yet by 
much too uncertain and variable to be per- 
mitted to stand as an established specific 
test. 
The distinction of serpents into poisonous 
and innoxious can only be known by an ac- 
curate examination of their teeth; the fangs 
or poisoning teeth being always of a tubular 
structure, and calculated for the conveyance 
or injection of the poisonous fluid from a pe- 
culiar reservoir communicating with the 
-fangs on each side of the head : the fangs are 
always situated in the anterior and exterior 
part of the upper jaw, and are generally, but 
not always, of much larger size than the 
other teeth ; they are also frequently accom- 
panied by some smaller or subsidiary fangs, 
apparently destined to supply the principal 
ones when lost, either by age or accident. 
The fangs are situated in a peculiar bone, so 
articulated with the rest of the jaw as to ele- 
vate or depress them at the pleasure of the 
•animal. In a quiescent state they T are recum- 
bent, with their points directed inwards or 
•backwards; but when the animal is inclined 
to use them as weapons of offence, their po- 
sition is altered by the peculiar mechanism 
of the above-mentioned bone in which they 
are rooted, and they become almost perpen- 
dicular. 
A general rule for the determination of 
the existence or non-existence of these or- 
gans in any species of serpent is proposed in 
a paper relative to the amphibia by Dr. 
Gray, and published in the Philosophical 
Transactions for the year 1788. r \ lie fangs, 
according to Dr. Gray, may be distinguished 
with great ease, and, as he believes also, 
with great certainty, by the following simple 
method. When it is discovered that there is 
something like teeth in the anterior and ex- 
terior part of the upper jaw, which situation 
lie considers as the only one in which venom- 
ous fangs are ever found, let a pin or other 
hard body be drawn from that part of the 
jj,\v to the angle of the mouth ; (which ope- 
ration may, for greater certainty, be tried on 
each side.) If no more teeth are felt in that 
line, it may, he thinks, be fairly concluded, 
that those first discovered are fangs, and tli*t 
the serpent is consequently venomous: if, 
on the contrary, the teeth first discovered are 
observed not to stand alone, but to be only a 
part of a complete row, it may as certainly 
be concluded that the serpent is not veno- 
mous. This rule, however, like most others, 
may have its exceptions, and perhaps the 
most legitimate test of real fangs in a serpent 
is their tubular structure, which may always 
be easily detected by the assistance of a pro- 
per magnifier. It is to be observed, that all 
serpents, whether poisonous or not, have be- 
sides the teeth, (whether fangs or simple 
teeth) in the sides of the upper jaw, two ad- 
ditional or interior rows, which are generally 
much smaller than the rest, and frequently 
scarcely visible: the general rule, therefore, 
is, that all venomous serpents have only two 
rows of true or proper teeth in the upper jaw, 
and that all others have four. 
A head entirely covered with small scales 
is in some degree a character, but by no 
means an universal one, of poisonous ser- 
pents; as are also carinated scales on the 
head and body, or such as are furnished with 
a prominent middle line. 
All serpents are in the habit of casting 
their skin at certain periods ; in temperate 
regions annually; in the warmer perhaps 
more frequently. The serpents of the tem- 
perate and cold climates also conceal them- 
selves, during the winter, in cavities beneath 
the surface of the ground, or in any other 
convenient places of retirement, and pass the 
winter in a state more or less approaching, in 
the different species, to complete torpidity. 
1 1 may be added, that some serpents are vi- 
viparous, as the rattlesnake, the viper, and 
many others of the poisonous kind, while 
the common snake, and probably the major 
part of the innoxious serpents, are oviparous, 
depositing their eggs in a kind of string or 
chain in any warm" an cl close situation, where 
they are afterwards Hatched. 
The broad undivided laminx or scaly plates 
on the bellies of serpents are termed scuta, 
and the smaller or divided plates beneath the 
tail are called squamae subcaudales, or sub- 
caudal scales; and from these different kinds 
of laminx the Linnxan genera of serpents are 
chiefly instituted. 
SERPENTARIUS. See Astronomy. 
SERPENTINE, a mineral found in amor- 
phous masses, forming strata, and even en- 
tire mountains. Its fracture is splintery, 
sometimes conchoidal. Specific gravity 2.57 
to 2.71; feels soft and almost greasy ; gene- 
rally emits an earthy smell when breathed on. 
Its culours are various shades of green, yel- 
low, red, grey, brown, and blue : commonly 
one or two colours form the ground, and one 
or more appear in spots or veins. Before the 
blowpipe it hardens, but does not melt. 
According to Mr. Chenevix it contains 
34.5 magnesia 
28.0 silica 
23.0 alumina 
4.5 oxide of iron 
0.5 lime 
10.5 water 
101.0 
SEJIPICULA, a genus of plants belonging 
to the class of monoecia, and to the order of 
tetrandria. The male calyx is quadridentate, 
and the corolla consists of four petals. The 
female calyx is divided into four parts, and 
the pericarpium is a tomentose nut. There 
are two species, the verticiliata and repens. 
SERPU LA, a gc-nus of insects of the order 
vermes testacea. The generic character is ; 
animal a terebella ; shell univalve, tubular 
generally adhering to other substances ; often 
separated internally by divisions at uncertain 
distances. There are 48 species. 
SERRATULA, saiv-xvort, a genus of 
plants belonging to the class of syngenesia, 
and to the order of polygamia xqualis. In 
the natural system it is ranged under the 49th 
order, compositx. The calyx is subcylin- 
drical, imbricated ; the scales of it pointed, 
but not spinous. There are 20 species : 1 . 
'I'he tinctoria, grows in woods and wet 
pastures. It dyes cloth of an exceedingly fine 
yellow colour, which stands well when fixed 
with alum. Goats eat this plant; horses are 
not fond of it ; cattle, swine, and sheep, leave 
it untouched. 2. The alpina, or mountain 
saw-wort, grows on high mountains, and 
flowers commonly in July or August. 3. 
The arvensis, corn saw-wort, or way- thistle, 
grows in cultivated grounds and by way-sides, 
and flowers in July or August. When burn- 
ed, it vields good ashes for making glass or 
fixed alkali. 
SERROPALPUS, a genus of insects of 
the order coleoptera : the generic character 
is, antennae setaceous ; feelers four, unequal ; 
the anterior ones longer deeply serrate, com- 
posed of four joints, the last joint very large, 
truncate, compressed, poteiliform ; the pos- 
terior ones subclavate: thorax margined, 
concealing the head, with a prominent angle 
on each side ; head deflected ; feet formed 
for digging. There are two species: the 
striatus is found on old wooden buildings in 
the evening in autumn. 
SERTULARIA, in natural history, a ge- 
nus belonging to the class of vermes, and to 
the order of zoophyta. The stem is radicat- 
ed, fibrous, naked, and jointed; the florets 
are hydrx, and there is one each joint. This 
genus comprehends 42 species of corallines. 
SERVANT. See Master and Servant 
SERVICE, in law, is a duty which a te- 
nant, on account of his fee, formerly owed 
to his lord. 
SERUM, a thin transparent liquor, which 
makes a considerable part in the mass of 
blood. 
The specific gravity of human blood is, at 
a medium, 1.0527. Mr. Fourcroy found the 
specific gravity of bullock’s blood, at the 
temperature oi (10°, to be 1.056. The blood 
does not uniformly retain the same consist- 
ence in the same animal, and its consistence 
in different animals is very various. It is 
easy to see that its specific gravity must be 
equally various. 
When blood, after being drawn from an 
animal, is allowed to remain for some time at 
rest, it very soon coagulates into a solid mass 
of the consistence of curdled milk. This mass 
gradually separates into two parts; one of 
which is fluid, and is called serum ; the other 
the coaguluni, has been called cruor, because 
it alone retains the red colour which distin- 
guishes blood. This separation is very similar 
to the separation of curdled milk .iilo curds 
and whey. 
