ex 



228 HANDBOOK OF INVERTEBRATE ZOOLOGY. 



lies under the posterior margin of the carapace, and the 

 following pairs are the appendages of the four free tho- 

 racic somites. Each of these appendages, the last excepted, 

 consists of a two-jointed protopodite, which carries an 

 exopodite and an endopodite, each of which is three- 

 jointed. All the segments of the limb carry long delicate 

 plumose setae upon their posterior or inner margins, and 

 stout, serrated, movable spines upon 

 their anterior or outer maro-ins. The 

 fifth thoracic appendage consists of a 

 basal joint and two spines, which appear 

 to represent the exopodite and endo- 

 podite. 



Fig. 121. — Second maxilla of Cyclops canthocar- 

 FiG. 121. poides. (FromClaus. ) 



d. Near the middle of the first abdominal seomient are 

 the large oval openings of the oviducts, one on each side 

 of the body. The margin of the opening is thickened and 

 is prolonged posteriorly into a projecting spine, which 

 probably serves to support the ovisacs. 



e. Make a drawing of the side view, showing these 

 points. 



III. The Digestive Tract. This is a nearly straight tube 

 which runs along the middle line from the mouth to the 

 anus. Its anterior end is large and its thick walls contain 

 large brown hepatic cells. The posterior portion is smaller 

 and more transparent, and exhibits active contractions. 

 In the anterior portion of the abdomen there is usually an 

 enlargement filled with partially-digested food, but it may 

 be absent, and its position is not constant. 



IV. The reproductive organs of the female consist of a 

 single ovary ^ two oviducts, and a spermatheca. 



