312 ARACHNIDK8. 



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, which 

 (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, narroAV, 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 narrow, 

 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 which belong to the tail. 

 In all other Arachnides, there are never more than three. 



The eight stigmata open into as many white bursse, 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 two vulvae. 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 f. 



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 Avith 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. 

 t For the anatomy of the Scorpion, see Treviranus, Marcel de Serres, and Leon 

 Dufour, Journ. de Phys., June 1817. 



