ORDER PULMONARIiE. 485 



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 certairf 

 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 ai*e 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 vulvae. 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 ai"achnides inhabit the hot countries of both hemi- 

 spheres, live on the ground, conceal themselves under stones 



2 F 2 



