A CYCLOPS. 51 



h) The last segment of the abdomen ends in a pair of diverging 

 caudal styles bearing plumose setae. 



i) The intestine may be seen through the body wall of the abdomen. 

 It ends in the anus on the dorsal surface of the last segment. Note 

 its rhythmic contractions which are supposed to facilitate the 

 circulation of a body fluid corresponding to blood. 



j) Dark, branched masses seen through the carapace represent repro- 

 ductive organs ovaries and oviducts, in case the specimen is a 

 female. 



Exercise i. Draw a view of the Cyclops, representing the animal as about 

 three inches in length. 



Examine a specimen from beneath or from the side and determine the 

 number of pairs of swimming feet. The last thoracic segment bears a 

 pair of vestigial limbs, and the abdominal segments have no appendages 

 at all. By careful inspection you may be able to make out a pair of 

 mandibles and two pairs of maxillae in the head region. Taking the 

 number of cephalic appendages as an index of the number of fused 

 segments in the head, determine that number. How many segments, 

 then, in each of the three regions of the body ? 



Exercise 2. Draw, on a large scale, one oj the antennules and a thoracic 

 leg. 



