Arachnids (6th Class)

These are oviparous animals with articulated limbs and eyes in the head.

They:

do not undergo a metamorphosis and never possess wings or elytra
have stigmata and limited trachaea for respiration
have a rudimentary circulation system
have several fertilizations in a lifetime

Observations

The arachnids, which in the order which we have established come after the insects, show clear progress in the perfecting of organic structure.

Sexual reproduction manifests itself with the arachnids, for the first time, with all its capabilities, since these animals couple and reproduce several times in their lives,

In the insects, the sexual organs, like those of plants, can only carry out a single fertilization.

The arachnids are the first animals in which the circulation system begins to become sketched out.

Cuvier writes that they have a heart extending from which, on the sides, are two or three pairs of vessels.

The arachnids:

live in the air, like those insects which have reached the perfect condition
do not undergo any metamorphosis
never have wings and elytra, something which is not the result of some abortion
remain hidden or living by themselves, feeding on prey or by sucking blood.

In the arachnids, the method of respiration is still the same as in the insects.

But the method is on the point of changing.

The trachaea of arachnids:

are very limited (impoverished)
do not extend to all the parts of the body

Cuvier writes that these trachaea have been reduced to a few vesicles.

After the arachnids, this method of respiration does not occur again in any of the classes of animals which follow.

This class of animals needs to treated with care. Many of them are venemous, especially those which live in hot climates.

Table of Arachnids

First Order: Arachnids Pedipalyps

No antenna, only pedipalps; the head fused with the thorax; eight limbs

Mygale Spider Phrynus Thelyphnus Scorpion

Pince Galeodes Faucheur

Trogul Elais Trombidium

Hydrachna Bdella Mite Nymphon Pycnogonum

Second Order: Arachnids with Antenna

Two antennae; a head distinct from the thorax

Louse Ricinus

Forbicina Podure

Scolopendre Scutigera Julus (millipede)