334 THE MICROSCOPIST. 



elliptica or cucumerina of the dog live in the lice which 

 infest dogs, and the dogs are infected by eating these lice. 

 Clinically, they are less important than cyst tapeworms. 

 Head small and hook apparatus imperfect. 



a. Head prominence with a single circle of small hooks. 



6. Tcenia Nana. Small. Anteriorly filamentous, but 

 larger near the middle. Once found in the duodenum of 

 a boy. 



7. T. Flaw Punctata. 33 cent. long. The anterior half 

 of immature joints 0.2 to 0.5 mm. long and 1 mm. broad, 

 which show behind the middle a large yellow spot. The 

 receptaculum filled with sperm. Head unknown. 



b. Papilla with multiple circle of hooks. 



8. T. Elliptica. Usually in dogs and cats. 



Family Bothriocephalidce. Head flattened. Two deep 

 fissure-like suckers. Articulations imperfectly marked. 



9. Bothriocephalus Latus. The largest human tape- 

 worm. Sometimes 5 to 8 meters long and from 3000 to 

 4000 short and broad joints, seldom more than 3.5 mm. 

 long, but 10 or 12 mm. broad. The last joints are nearly 

 square. Anterior end threadlike. Proglottides pass away 

 in lengths (from 2 to 4 feet). Ova oval, with transparent 

 shells, and a lid at one end through which the embryo 

 slips into the water. The six-hooked embryo is developed 

 several months after the ova are passed. 



10. B. Cordatus. Smaller than B. latus. Head short 

 and broad, heart-shaped. 



2d Order. Trematodes. Suckerworms. Parasitic solitary 

 flat worms, with inarticulate leaf-shaped bodies ; with 

 mouth and bifurcated intestinal canal, without anus, 

 with abdominal prehensile apparatus. Male and female 

 organs mostly in the same individual. The distomata 

 go through a complicated alternate generation and 

 metamorphosis. The embryos escape from the ova 

 into water and seek a new animal habitat, mostly 

 snails. Here they develop into cyst-germs, which are the 

 parents of the Cercarice, which have a rudder-like tail and 



