356 
CLASS CRUSTACEA. 
pair of feet. The others are more solid or corneous, with a 
range of small spines at the posterior edge ; the last is larger 
than the preceding, almost square, depressed, angular, and 
terminated by two filaments or articulated seta3. In some 
species composing the genus Lepidurus of Dr. Leach, we 
observe in their interval a corneous lamina, flatted, and ellip- 
tical. If the number of feet is about a hundred and twenty, 
the last rings, commencing with the eleventh or twelfth, must 
support more than one pair, which, in this point of view, 
approximates these Crustacea to the myriapoda. The testa, 
perfectly free from its anterior attachment, covers a large 
portion of the body, and thus protects the first segments, 
which, as we have observed, are of a softer consistence than 
the following: it consists of a large corneous shell, very 
slender, almost diaphanous, representing the upper teguments 
of the head and of the thorax united, and forming a large 
oval buckler, convex, notched in the manner of an angle, and 
denticulated at its posterior extremity. It is divided at its 
upper face by a transverse line forming two united arches, 
into two areas, the anterior of which, almost semi-lunar, 
answers to the head, and the other to the thorax. The 
first presents, in the middle, three simple eyes, or without 
any sensible facettes, very closely approximated, the anterior 
two of which are larger, almost in the form of a kidney, and the 
posterior of which is much smaller and oval. A duplicature 
of the anterior portion of the testa forms underneath a sort of 
frontal buckler, flatted, in the form of a half-moon, and serving 
as a basis to the labrum. The posterior area, that which 
corresponds to the thorax, is carinated at the middle of 
its length. This testa is fixed only by its anterior extremity, 
so that from this point the entire back of the animal may be 
uncovered. The sides of this shell, viewed underneath, and 
by the light, present each a large spot, formed of a great num- 
ber of lines, describing concentric ovals, and which appear 
