362 
CLASS CRUSTACEA. 
they are composed of six articulations, comprehending the 
mobile finger of the forceps. These have an additional articu- 
lation, and differ besides from the preceding, in having exter- 
nally at their base, an arched appendage, inclining back- 
wards, of two articulations, the last of which is compressed 
and obtuse; also their fifth articulation is terminated at the 
internal side, by five small mobile leaflets, corneous, narrow, 
elongated and pointed, and, moreover, the two fingers of the 
forceps are mobile, or articulated at their base. The two 
pieces situated in the interval of these feet, which M. Savigny 
considers as a ligula, appear to me to be but two maxillary 
lobes of these organs, but detached or free. The pharynx 
occupies the interval comprised between all these feet. The 
males are distinguished from the females by the form of the 
forceps, which terminate the two or four anterior ones. They 
are swelled, and destitute of the mobile finger. The last two 
feet of this buckler are united, and in the form of a large mem- 
branaceous leaflet, almost semicircular, supporting the sexual 
organs at its posterior face, and presenting in the middle of 
an emargination of the posterior edge, two small triangular 
divisions, elongated and pointed, which appear to represent 
the internal fingers of the forceps. Some sutures indicate 
the other articulations. The second piece of the testa, arti- 
culated with the preceding, at the middle of its posterior 
emargination, and filling the vacancy which it forms, is 
almost in the form of a triangle, truncated and emarginated 
angularly at its posterior extremity. Its lateral edges are 
alternately emarginated and denticulated, and the emargina- 
tions, beginning from the second, present each in their 
middle an elongated and mobile spine. There are six on 
each side. In the inferior concavity are enclosed, and dis- 
posed by pairs, ten fin-feet, almost similar, in form, to the last 
two feet, but united simply at their base, applied one upon the 
other, and supporting at their posterior face, the gills, which 
