ON CRUSTACEA. 241 



fishes on which they live. The avguli have three sorts of 

 feet ; the first tvro hke cupping-glasses, round, and broad ; 

 the second with two hooks, proper for prehension, and the 

 others, eight in number, soft, fleshy, and terminated by a fifi 

 formed of two leaflets. 



Finally, the names of hranchiopoch, phyllopa, &c. have been 

 appropriated to those entomostraca, whose feet are at once both 

 organs of locomotion and of respiration. Apus, limnadia, and 

 branchipus, which present this mode of conformation, have 

 often a great number of these ffill-feet ; there are sixty pair at 

 least in apus, eleven in branchipus, and two and-twenty in 

 limnadia. They are all composed of several thin and soft 

 laminae, diversely configurated, articulated together, and one, 

 at least, of their edges furnished with numerous hairs. In 

 apus, the first of these feet have four articulated threads, the 

 two upper resembling antennae ; all the others have, under- 

 neath, near their base, an ovaliform, vesicular sac, and those 

 of the eleventh pair, support a capsule, with two valves, 

 which incloses the eggs. 



These animals, like the insects, have their functions very 

 distinct, and accordingly, like them, they should occupy an 

 elevated rank in the series of beings. Being provided with 

 articulated members, they are evidently in the relation of the 

 locomotive faculty superior to the mollusca, and annelides, as 

 well as to the radiated and infusory animals. All of them 

 possess a nervous system, whose first centres, and first rami- 

 fications are easily to be observed. They are scarcely ever 

 destitute of the organ of vision. In some of them the organ of 

 hearing has been discovered, and every thing goes to prove, 

 that the senses of taste and smell exist in the Crustacea, 

 as well as in the insects, although the peculiar seats of these 

 senses have not yet been recognized. In these respects it is 

 certain that the Crustacea have the priority over ^ery many of 



VOL. XIII. R 



