3250 



THE JOINTED ANIMALS 



OAR-FOOTED GROUP Order COPEPODA 



In the free-living members of this group, the body is elongate and segmented- 

 the thorax bears four or five two-branched swimming feet, and the abdomen is 

 without appendages. A common fresh-water form is Cyclops, the structure of 

 which serves as a type of that of the order. The body is broad in front and 



FISH LICE. 



a. Lern&onema (enlarged 3 times); b. Brachiella (enlarged 9 times'*; c. Pennella (enlarged 5 times); d. Ha-mo- 

 baphes (natural size); e. Caligus (enlarged 3 times). 



tapering behind, being thus pear shaped in outline. The normal five pairs of head 

 appendages are well developed, the first pair of antennae being long and acting as 

 oars. The dorsal elements of the head are fused to form a carapace, which bears 

 a single eye in front and is behind united to the first thoracic segment, the remain- 

 ing five of this region being free. The abdomen consists of four narrow cylindrical 



