AM PH IPO DA. 297 



MALACOSTRACA. 



b. Eyes sessile and immoveable. 



The Branchiopoda are the only Crustacea of which we shall henceforward 

 have occasion to speak, that exhibit eyes placed on pedicles. But independently 

 of the fact that these pedicles are neither articulated nor lodged in special 

 cavities, the Branchiopoda have no shell, and are otherwise removed from the 

 preceding Crustacea by various characters. All the Malacostraca of this divi- 

 sion are also deprived of a shell; their body, from the head downwards, is 

 composed of a suite of articulations, of which each of the first seven is furnished 

 with a pair of feet, the following and last ones, seven at most, forming a sort 

 of tail terminated by fins or styliform appendages. The head presents four 

 antennae, the two intermediate superior, two eyes, and a mouth composed of 

 two mandibles, a tongue, two pairs of jaws, and a sort of lip formed by two 

 foot-jaws that correspond to the two superior ones of the Decapoda; here, as 

 in the Stomapoda, the flagrum no longer exists. The four last foot-jaws are 

 transformed into feet, sometimes simple and at others constituting a claw, but 

 almost always with a single toe or hook. 



All these Crustacea are small, and mostly inhabit the sea-coast or fresh water. 

 Some are terrestrial, and others are known which are parasitical. 



ORDER III. 



AMPHIPODA. 



TnEAmphipoda are the only Malacostraca with sessile and immoveable eyes, 

 whose mandibles, like those of the preceding 

 Crustacea, are furnished with a palpus, and the 

 only ones whose subcaudal appendages, always 

 very apparent, by their narrow and elongated 

 form, their articulations, bifurcations, and other incisures, as well as by the 

 hairs or cilia with which they are provided, resemble false or natatory feet. In 

 the Malacostraca of the following orders, these appendages have the form of 

 laminae or scales; here these hairs and cilia appear to constitute the branchiae. 

 Many of them, like the Stomapoda and the Lsemodipoda, have vesicular bursae 

 either between their feet or at their external base, the use of which is unknown- 

 The first pair of feet, or that which corresponds to the second foot-jaws, is 

 always annexed to a particular segment, the first after the head. The an- 

 tennae, which, with a single exception the Phronimae, are four in number, 

 project, gradually taper into a point, and consist, as in the preceding Crustacea, 

 of a peduncle and a single stem, or one furnished at most with a little lateral 

 branch, and usually composed of several joints. The body is generally com" 



