ON CRUSTACEA. 
235 
gular, formed of four pieces, and covering like a lip, but 
longitudinally, all the parts of the mouth which have been 
just mentioned. After these come eight pairs of appendages 
or members, to which it is difficult to assign precise names, 
and five of which surround the mouth. M. Savigny considers 
the first two as auxiliary jaw T s, and the other fourteen as 
feet. 
The Crustacea, with sessile eyes, amphipods, and isopods 
in general, besides the upper lip, palpigerous mandibles, car- 
tilaginous bifid tongue, and two pair of jaws with two laminae 
and without palpi, have also an under lip resulting from the 
union of the two jaw-feet, or auxiliary jaws. There are, 
farther on, fourteen feet, properly so called. In bopyrus, the 
principal parts of the mouth are indistinct, but its orifice is 
covered by two anterior membranaceous pieces, a little convex, 
under which are two appendages, soft, compressed, and placed 
on each side, like the jaws in the other Crustacea. 
In the entomostraca, the limulse are equally anomalous, as 
the squilkn among the malacostraca. The pharynx is placed 
in the middle of ten appendages in the form of feet or claws. 
The haunches of these appendages, situated on the sides of 
the aperture of the oesophagus are spiny, and serve as jaws 
for the trituration of the aliments. In front, are two ap- 
pendages, called by M. Savigny, succedaneous mandibles, 
and palpi by Baron Cuvier, also in the form of forceps, but 
much smaller than the others, and annexed to the sides of a 
lanceolate, flatted piece, which is composed of their haunches 
united, and which M. Savigny considers as performing the 
functions of an upper lip. The posterior edge of the pharynx 
presents a piece, also flatted, but bifid, and which may be re- 
garded as the lower lip, formed by the union of the haunches 
of a pair of feet not developed. There are no true mandibles 
or antenna). 
In apus the mouth more resembles that of the Crustacea 
