ENT0M08TRA CANS. 
87 
number of legs having meanwhile increased, are enclosed 
by two sets of valves, so that the animal appears as if bi- 
valved (Fig. 102), and at last the barnacle-shape is at- 
tained. 
Order 2. Eatomostraca (Water-fleas). — The type of this 
group is Cyclops (Fig. 103), in which the body is pear- 
e 
FiQ. 103.— Ci/dops. e, eye; /i, heart; Fig. 104.— Lernaea of Fig. 105.. — Fish 
egr, egrgs ; /, f eet. Highly mag- the cod. /i, head;ov, louse of the 
nified. ovary. Nat. size. menhaden. 
shaped, with a single bright eye in the middle of the head; 
it has two pairs of antennae, used for swimming as well as 
feelers; biting mouth-parts^ and short legs. The females 
swim about with two egg-masses attached to the base of 
the abdomen. The young is a Nauplius, much like that 
represented in Fig. 112), the mouth-organs, the legs and 
