62 HELMINTHOLOGY 



pores projecting at the lateral borders and alternating irregu- 

 larly. 



E. g. Tcenia solium, the pork tapeworm of man. The ros- 

 tellum is short and is provided with a double circle of hooks. 

 The average length of the tapeworm is said to be from 8 to 12 

 feet, with 800 to 900 proglottides. The mature proglottides 

 measure from " 10 to 12 mm. in length by 5 to 6 mm. in breadth." 

 (Braun.) The larva is Cysticercus celMosa, whose habitat is 

 the connective tissue of swine. 



2. Genus Dipylidium. "Rostellum retractile, armed with 

 several transverse rows of alternating hooks; hooks with small 

 roots, the base being discoidal; mature segments elongate with 

 double sets of genital organs; pores double and opposite; ova 

 with double transparent membranes." (Stiles.) 



E. g. Dipylidium caninum, tapeworm of dogs, also found in 

 cats, and occasionally in man, measures from 6 to 12 inches in 

 length. The mature proglottides are about J4 mcn long by y 

 inch wide, and have the form of cucumber seed, hence the 

 synonym, Tania cucumerina. The cysticercus of this tape- 

 worm is found in the cat and dog flea, Ctenocephalis canis, and 

 the biting dog louse, Trichodectes latus. 



3. Genus Drepanidot&nia. "Head provided with a single row 

 of uniform hooks, few (8-20) in number, with dorsal root much 

 longer than ventral root, the latter always small; with prong 

 directed posteriorly when the rostellum contracts." (Stiles.) 



E. g. Drepanidotcenia infundibuliformis is a common tape- 

 worm of poultry. This is described as follows: "20-130 mm., 

 rarely 230 mm. long. Head globular, rather depressed; ros- 

 tellum elongate, cylindrical or hemispherical, swollen at sum- 

 mit, armed with a single row of 16-20 hooks. . . . Suckers 

 rather small. Neck very short; anterior segments very short, 

 the following ones funnel-shaped, the anterior border being 

 much narrower than the posterior border; posterior segments 

 almost as long as broad; genital pores irregularly alternate." 

 (Stiles.) 



