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ARACHNIDES. 
This class constituted Linnaeus’s last order of his insects, but 
Lamarck formed a distinct class for them. They possess func¬ 
tions different from both crustaceous animals and insects ; from 
the former, in having always internal respiratory organs, and 
from the latter, in not undergoing any transformation. The 
head is not distinct from the trunk of the body; and they have 
from two to eight simple eyes ; the usual number of feet are 
eight, although some few have six only. The body of all this 
class is soft, except one tribe. 
Lamarck has divided this class into three orders, but La- 
treille only separates them into two, as follow:— I. Pulmonari^e, 
II. Trachearee. 
ORDER I.—PULMONARRE. 
Provided with a heart, or organ of circulation; branchial sacs 
placed on each side of the abdomen below ; the sexual organs 
are double; with from six to eight smooth eyes ; they are fur¬ 
nished with two pedipalpi, with one or two toes at their termi¬ 
nation, one of which is always moveable; two jaws, and palpi, 
and four pairs of feet. 
Section I. — Pedipalpj. 
With very large palpi; abdomen annulated; and devoid of 
web-spinning papillae ; sexual organs situated at the base of the 
abdomen. 
TRIBE I.-SCORPIONIDES. 
Abdomen sessile, with four spiracles below on each side, and 
the last six segments forming a knotty tail, the last one ending 
in a point, acting as a sting, and perforated for the secretion of 
poison ; palpi in the form of forceps. There is but one genus of 
this tribe. 
Genus 1.—SCORPIO.— Linnaus. 
Generic Character. — Two large palpi, in the form of arms, 
the last joint thickest, and terminated by forceps ; mandibles 
short, thin, and didactyle; jaws short and rounded ; eyes six or 
eight; body oblong, divided into segments, with a long knotted 
