50 
The Double-Pored Dog Tapeworm — DIPYLIDIUM CANINUM « (Linnaeus, 1758). 
[Figs. 74 to 80.] 
Specific diagnosis. — Dipylidium: Strobila 15 to 35 cm. long; head small, globular; 
rostelluin club-shaped, with 3 to 4 rows of hooks (about 60 in number), of rose- 
thorn form; the anterior hooks 15//, the posterior 6ju ; suckers, relatively large, rather 
elliptical. Segments 80 to 120 in number; gravid segments 8 to 11 mm. long, 1.5 to 
Fig. 77. — Head of same, showing four rows of rose-thorn hooks on the rostellum and four unarmed 
suckers. Greatly enlarged. (After Stiles, I§03, fig. 4.) 
Fig. 78. — Egg packet of same, greatly enlarged. (After Stiles, 1903, fig. 5.) 
Fig. 79. — Egg of same. Note the six hooks in the embryo. Greatly enlarged. (After Stiles, 1903, 
fig. 6.) 
Fig. 80. — Cryptocystis trichodectis, the cystic (infecting) stage of Dipylidium caninum, as found in the 
ilea. (After Leuckart, 188G, 817, fig. 34S.) 
3 nun. broad, often reddish in color. Genital pores at equator or in posterior half of 
segment; uterus forms egg capsules, each containing 8 to 20 ejrgs; eggs globular, 43 to 
50 /t in diameter; egg shell thin; onchosphere 32 to 36 /g 
Habitat. — Adults in small intestine of dogs ( Cards fam iliaris) and cats ( Fells catus ); 
occasionally as accidental parasite in man. Larvae in lice ( Trichodec.tes canis) and fleas 
( Ctmocephalus canis and Pal ex irritans). 
Geographic distribution. — Probably more or less cosmopolitan. 
a Synonyms. — Taenia canina Linnaeus, 1758a; .T. moniliformis Pallas, 1781 (not 
Batsch, 1786a); T. cucumerina Bloch , 1782a; T. cateniformis Goeze, 1782a; T. elliptica 
Goeze, 1782a; T. ellyptica Batsch, 1786a; T. moniliformis Schrank, 1788; T. cateniformis 
canina Linnaeus of Gmelin, 1790a; T. cateniformis fells Gmelin, 1790a; Alyselrninthus 
ellypticus (Batsch, 1786a) Zeder, 1800a; Halysis ellyptica (Batsch, 1786a) Zeder, 1803a; 
Tenia canina (Linnaeus, 1758a) Beneden, 1861a; T. cucumerina (Bloch, 1782a) Beneden, 
1861a; Teenia [( Dipylidium)^ cucumerina Bloch of Leuckart, 1863; Cryptocystis trie) 10 - 
dectis Yillot, 1882; Dipylidium caninum (Linnaeus, 1758a) Railliet, 1893a. 
Bibliography. — See Diamare, 1893b. 
