ORDER PULMON A RITE . 
435 
of small laminae, united with it by an articulation, narrow, 
elongated, hollow internally, parallel, and resembling the 
teeth of a comb. Their number is more or less considerable, 
according to the species ; sometimes it varies within a certain 
quantity, and perhaps according to age in the same species. 
The use of these appendages has not yet been ascertained by 
any positive experiments. The four following rings have 
each a pair of pulmonary sacs and stigmata ; immediately 
after the sixth, the abdomen suddenly grows narrow, and the 
other six rings, in the form of knots, compose the tail. All 
the tarsi are similar, having three articulations, with two hooks 
to the end of the last. The last four feet have a common 
base, and the first articulation of their haunches is soldered; 
the last two are even partly set back to the abdomen. 
The two nervous cords proceeding from the brain, are 
united at intervals, and form seven ganglia, the last of which 
belongs to the tail. In all the other arachnides, the number of 
ganglia is but three at most. 
The eight stigmata open into as many white pouches, each 
enclosing a great number of small and very slender laminae, 
between which it is probable that the air is filtrated. A 
muscular vessel runs along the back, and communicates with 
each pouch by two vessels : other branches proceed from it 
to all parts. The intestinal canal is straight and narrow ; 
the liver is composed of four pairs of glandular clusters, which 
pour their fluid into four points of the intestine. The male 
has two penes issuing forth near the combs, and the female 
two vulva). These last open into a matrix composed of 
several canals, which communicate one with another, and 
which we find at the time of parturition filled with living 
young. The testicles are also formed of certain vessels anas- 
tomosed together. 
These arachnides inhabit the hot countries of both hemi- 
spheres, live on the ground, conceal themselves under stones 
2 F 2 
