ON CRUSTACEA. 235 



gular, formed of four pieces, and covering like a lip, but 

 longitudinally, all the parts of the mouth which have been 

 |ust mentioned. After these come eight pairs of appendages 

 Dr members, to which it is difficult to assign precise names, 

 md five of which surround the mouth. M. Savigny considers 

 he first two as auxiliary jaws, and the other fourteen as 

 feet. 



The Crustacea, with sessile eyes, amphipods, and isopods 

 n general, besides the upper lip, palpigerous mandibles, car- 

 ilaginous bifid tongue, and two pair of jaws with two laminas 

 md without palpi, have also an under lip resulting fi'om the 

 mion of the two jaw-feet, or auxiliary jaws. There are, 

 "arther on, fourteen feet, properly so called. In bopyrus, the 

 Drincipal parts of the mouth are indistinct, but its orifice is 

 covered by two anterior membranaceous pieces, a little convex, 

 inder which are two appendages, soft, compressed, and placed 

 m each side, like the jaws in the other Crustacea. 



In the entomostraca, the limulae are equally anomalous, as 

 ,he squillse among the malacostraca. The pharynx is placed 

 n the middle of ten appendages in the form of feet or claws, 

 riie haunches of these appendages, situated on the sides of 

 he aperture of the oesophagus are spiny, and serve as jaws 

 or the trituration of the aliments. In front, are two ap- 

 jendages, called by M. Savigny, succedaneous mandibles, 

 md palpi by Baron Cuvier, also in the form of forceps, but 

 nuch smaller than the others, and annexed to the sides of a 

 anceolate, flatted piece, which is composed of their haunches 

 mited, and which M. Savigny considers as performing the 

 unctions of an upper lip. The posterior edge of the pharynx 

 Dresents a piece, also flatted, but bifid, and which may be re- 

 garded as the lower lip, formed by the union of the haunches 

 )f a pair of feet not developed. There are no true mandibles 

 )v antennae. 



In apus the mouth more resembles that of the Crustacea 



