ZOOLOGY, 
innocent, but otliers have fangs, by which 
ttiey instil a poisonous fluid into the wounds 
that they make. In England the viper is 
the only venomous serpent; it is known by 
its dark brown colour, and by a stripe of 
whitish spots running along its back; but 
to mankind its bite is seldom, if ever fatal. 
The first tfiree classes of animals have 
lungs, as we have rfready seen, for respira- 
tion, and receive air by the mouth; those 
which have gills, and red blood, are fishes, 
residing either in fresh or in salt water, or 
indifferently in both: their eggs are involv- 
ed in a membrane, and have no albumen. 
Of the six orders of fishes, four have re- 
gular gills, supported by little bones; and 
they are distinguished, according to the 
place of their ventral fins, into Apodes, as 
the eel and lamprey : Jugulares, as the cod : 
Thoracici, as the sole and perch : and Ab- 
dominales, as the salmon and pike; dis- 
tinctions which appear to be perfectly arti- 
ficial, although useful in a systematic ar- 
rangement. The two remaining orders are 
without bones in the gills, those of the one 
being soft, and of the other cartilaginous or 
gristly. These are the Branchiostegi and 
Chondropterygii of Artedi, which Linnaeus, 
from a mistake, classed among the Amphi- 
bia. The sun fish, the lump fish, the fish- 
ing frog, and the sea-horse, are of the for- 
mer, and the sturgeon, the skate, and the 
shark, of the latter order. 
Insects derive their name from being al- 
most always divided, into a head, thorax, 
and abdomen, with very slender intervening 
portions : although these divisions do not 
^ist in all insects. They are usually ovi- 
parous ; they respire, bat not by the mouth ; 
they have a number of little orifices on 
each side of the abdomen, by which the 
air is received into their ramified trachea; 
and if these are stopped with oil, they are 
suffocated. Instead of bones, they have a 
hard integument or shell. Their mouths 
are formed on constructions extremely va- 
rious, but generally very complicated : Fa- 
bricius has made these parts the basis of his 
classification ; but from their minuteness in 
most species, the method is, in practice, in- 
superably Inconvenient : and the only way, 
in which such characters can be rendered 
really useful, is when they are employed in 
the subdivision of the genera, as determined 
from more conspicuous distinctions. In- 
sects have most frequently jaws, and often 
several pairs, but they are always so placed 
as to open laterally or horizontally. Some- 
times, instead of jaws, they have a trunk, 
VOL. VI. 
or proboscis. In general, they pass through 
four stages of existence, the egg, the larva, 
or stage of growth, the pupa, of chrysalis, 
which is usually in a state of torpor or com- 
plete inactivity, and the imago, or perfect 
insect, in its nuptial capacity. After the 
last change, the insect most frequently 
takes no food till its death. 
The Linnaean orders of insects are the 
Coleoptera, with hard sheaths to their 
wings, generally called beetles; the Hem ip- 
tera, of which the sheaths are of a softer 
nature, and cross each other, as grasshop- 
pers, bugs, and plant lice: tlie Lepidop- 
tera, with dusty scales on their wings, aS 
butterflies and moths; the Neuroptera, as 
the libellula, or dragon-fly, the may-fly, and 
other insects with four transparent wdngs, 
but without stings; the Hyraenoptera, 
which have stings, either poisonous or not, 
as bees, wasps, and ichneumons ; the Dip- 
tera, with two wings, as common flies and 
gnats, which have halteres, or balancing 
rods, instead of the second pair of wings ; 
and, lastly, the Aptera, without any wings, 
which form the seventh order, comprdiend- 
ing crabs, lobsters, shrimps and prawns, for 
these are properly insects; spiders, scor- 
pions, millepedes, centipedes, mites, and mo- 
noculi. The Monoculus is a genus includ- 
ing the little active insect.s found in pond- 
water, which are scarcely visible to the 
naked eye, as well as the Molucca crab, 
which is the largest of all insects, being 
sometimes six feet, long. Besides these 
there are several genera of apterous insects 
which are parasitical and infest the human 
race as well as other animals. 
The Vermes are the last and lowest of 
animated beings, yet some of them are not 
deficient either in magnitude or in bdauty. 
The most natural division of vermes is into 
five orders ; the Intestina, as earth-worms 
and ascarides, which are distinguished by 
the want of moveable appendages, or ten- 
tacnla, from the Mollusca, such as tire dew- 
snail, the cuttle fish, the sea anemone, and 
the hydra, or fresh water polype. The 
Testacea have shells of one or more pieces, 
and most of them inhabit the sea, and are 
called shell fish, as the limpet, the periwin- 
kle, the snail, the muscle, the oyster, and 
the barnacle. The order Zoophyta con- 
tains corallines, sponges, and other com- 
pound animals, united by a common habita- 
tion, which has the general appearance of a 
vegetable although of animal origin; each 
of the little inhabitants, resembling a hy- 
dra, or polype, imitating by its extended 
Rr 
