312 
ARACHNIDKS. 
simple eyes, forming a curved line, and near the middle of the back 
two others, also simple, which are approximated. The palpi are 
very large, with a forceps at the 'extremity resembling a hand ; their 
first joint forms a concave and rounded jaw. There is a triangular 
appendage at the origin of each of the four anterior legs, Avhich 
(appendages) by their approximation have the appearance of a qua- 
dripartite lip ; the two lateral divisions, however, may be considered 
as a kind of jaws, the remaining two forming the ligula. The abdo- 
men is composed of twelve annuli, those of the tail included ; the first 
is divided into two parts, of which the anterior bears the sexual 
organs, and the other the two combs. These appendages are com- 
posed of a principal, narrow, elongated, and articulated piece, 
moveable at base, and furnished along its inner side with a suite of 
little hollow laminae, united to it by an articulation, that are narroAV, 
elongated, parallel, and similar to the teeth of a comb; their num- 
ber is more or less considerable according to the species ; it varies to 
a certain extent, and perhaps with age, in the same species. No 
positive experiment has yet determined the use of these appendages. 
The four following annuli have each a pair of pulmonary sacs and 
stigmata. Directly after the sixth, the abdomen becomes suddenly 
narrowed, and the remaining six, under the form of joints, compose 
the tail. All the tarsi are alike, and consist of three joints, with two 
hooks at the end of the last. The four last legs have a common 
base, and the first joint of the hip is soldered ; the two last are even 
partly fixed against the abdomen. 
The two nervous cords, proceeding from the brain, unite at inter- 
vals and form seven ganglions, the last of Avhich belong to the tail. 
In all other Arachnides, there are never more than three. 
The eight stigmata open into as many Avhite bursae, each contain- 
ing a great number of very slender, small laminae, between which it 
is probable that the air passes. A muscular vessel extends along the 
back, and communicates with each bursa by two branches*; it also 
distributes vessels to every part of the animal. The intestinal canal 
is straight and slender. The liver is composed of four pairs of 
glandular clusters, which pour their humour into the intestine at 
four points. The male has two copulating organs arising near the 
combs, and the female has tavo vulvee. The latter open into a matrix 
consisting of several inter-communicating canals, which in the proper 
period are found filled with living young ones; the testes are also 
formed of some anastomosing vessels |. 
These Arachnides inhabit the hot countries of both hemispheres, 
live on the ground, conceal themselves under stones and other bo- 
dies, most commonly in ruins, dark and cool places, and even in 
houses. They run with considerable swiftness, curving their tail 
over their back. They can turn it in every direction, and use it for 
the purposes of attack and defence. With their forceps they seize 
Onisci and various insects, Caribici, Orthoptera, &c., on which they 
* See our preceding remarks on the circulation of the Arachnides Pulmonariae. 
"h For the anatomy of the Scorpion, see Treviranus, Marcel de Serres, and Leon 
Dufour, Journ. de Phys., June 1817. 
