THE LEECHES 55 



a. Under a moderately high power of the microscope, note 

 that the filarise have an eel-like form, with the anterior portion 

 truncated, while the posterior portion gradually tapers off to a 

 point. 



b. Notice the clear sheath enclosing the entire worm. The 

 mosquito, Culex fatigans, is the intermediary host for the 

 species. 



Draw the specimen. 



C. Examine and draw filariae in a blood smear from a ground- 

 squirrel. 



D. Examine specimens of Filaria ceruina, a filarious worm 

 inhabiting the peritoneum of cattle and other ruminants. Note 

 the number of papilla around the mouth, the number of spicules 

 in the male, and whether the vulva of the female is anterior or 

 posterior. 



EXERCISE 30b 



THE LEECHES 

 PHYLUM ANNELIDA, CLASS HIRUDINEA 



A. Characteristics of Annelida (Annulata). Worms belonging 

 to the Phylum Annelida consist of a series of rings or segments; 

 there are no jointed appendages, the alimentary canal is well 

 developed. 



B. Characteristics of Hirudinea. The leeches are character- 

 ized by the possession of a sucker at each end of the body; the 

 internal segmentation and the number of body rings do not 

 correspond. 



C. With a specimen of a leech before you, notice the following 

 parts: 



a. The mouth, situated in the anterior sucker. 



b. The anus is located dorsal to the posterior sucker. 



c. Count the number of segments or annuli. 



