520 
SUPPLEMENT 
largest, almost square, or triangular, occupying the place of 
head or corslet, supporting two or four simple eyes, situated 
laterally, the organs of mastication, two palpated feet, large, 
in the talon form, terminated by a didactylous forceps, and 
the first six feet ; 2. of eleven other segments, but transverse, 
annuliform, and on the first of which, the fourth, and last 
pair of feet, appear to be inserted ; the subsequent rings com- 
pose the abdomen. The mouth is formed, 1st. of two mandi- 
bles, situated at the anterior and superior extremity of the 
corslet, contiguous, advanced, and entirely uncovered in the 
obisia, corneous, of a single piece in the form of a forceps, ovoid, 
didactylous, and of which the external digit is mobile, denticu- 
late, or ciliated ; 2. of two large palpated feet, or claws, ter- 
minated also in a didactylous forceps, composed of six articu- 
lations, the mobile digit included ; 3. of two jaws, formed by the 
internal prolongation of the radical articulation of the claws, 
valvular, a little gibbous, or convex in the middle, depressed, 
and with reflected edges, near the internal margins, joining along 
these margins, thus closing the mouth inferiorly, and terminated 
in a point ; 4. of a sternal tongue, situated in the interior of 
the mouth, between the jaws and mandibles, cuspidated at its 
superior extremity, and presenting, at each side of this point, 
a small appendage, according to the observations of M. 
Savigny. The younger Hermann had already observed this 
piece ; he says that it is a conical papilla, embraced by two 
sorts of valvules, (the jaws) and that it is doubtless the 
proboscis of these animals. The feet are divided into five 
( chelifer , properly so called) or six articulations, (the obisia) 
according as the tarsus is composed of one or two pieces. 
The extremity of the last articulation is always armed with 
hooked, elongated, and approximated teeth, under which is a 
small pellet. The articulation which corresponds to the 
thigh is in general broader, and elongated. The length of the 
