DAPHNIAD.E. 267 



Order CLADOCERA* 



Body, except head, which projects, quite enclosed in two 

 shells, joined on the back. Feet four to six pairs ; joints 

 partly cylindrical, and partly foliaceous and branchiform. 

 Eye single, and very large. Two pairs of antennae ; the 

 lower branched, large, and used in swimming. Mandibles 

 without palpi. 



Fam. DAPHNIADJE, Baird. 



Upper antennae generally very small ; lower large, gene- 

 rally two-branched. Five or six pairs of feet, enclosed 

 within the shell. Intestine straight. 



Feet in constant motion, and giving an undulatory motion 

 to the water, and establishing a current towards the mouth. 

 Dr. Baird informs us that the various species of this 

 family are only to be met with in fresh-water, generally in 

 ponds and ditches, some preferring those in which there is 

 much duckweed (Lemna) floating on the surface; others 

 delighting in horseponds where cattle come to drink. They 

 are often found in myriads; and as some of the species 



* KKados, a branch, and Ktpas, a horn ; from their branched antenna;. 



