78 FROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55. 



15. Forms with tlie books from 170 to 294 ii long. Bladderworms attached 



to omenta, mesenteries, or peritoneal serosa 16. 



Forms with the large hooks 185 to 145 m long. Probably accidental parasites 

 of the dog 17. 



16. Large hooks 225 to 294 ^ long. Testes extend posterior of the vitellarium. 



Mature segments approximately square. Gravid segments with 8 to 14 

 lateral branches on each side. Vagina only slightly dilated and curved 

 near margin of segnrent. Bladderworm in rabbits, rarely in mous© or 



beaver Taenia ■pisiformis, p. 22. 



Large hooks 170 to 224 ix long. Testes do not extend posterior of the 

 vitellarium. IMature segments distinctly wider than long. Gravid seg- 

 ments with 5 to 10 lateral branches on each side. Vagina forms a sort 

 of crescent by dilation and curvature near lateral margin of segment. 

 Gravid segments with a median longitudinal groove terminating in a 

 notch posteriorly. Bladderworm usually in ruminants, also reported from 

 monkeys and rodents Taenia hydati'jena, p. 28. 



17. Guard of small hook twisted so that its flat surface tends to lie in the plane 



of the blade and handle Taenia Iracfii/soma, p. 21. 



Guard of small hook not so twisted 18. 



18. Head acorn-shaped, with hooks far anterior of the suckers. Mature seg- 



ments approximately square Taenia haJaniccps, p. 16. 



Head not acorn-shaped, and hooks not far anterior of suckers. Mature seg- 

 ments distinctly broader than long Taenia Jjrauni, p. 19. 



19. Strobila not over 25 mm. long ; rostellum with 4 circlets of hooks, the hooks 



45 pi long and with a handle and guard ; the cirrus pouch opens ventral of 



the vagina; 1 egg to each egg capsule Dipylidium trinchesei, p. 69. 



Strobila 5 cm. long or longer ; hooks rose-thoru-shaped 20. 



20. Head with IG circlets of hooks; strobila 20 to 30 cm. long; 1 egg to each 



egg capsule Dipylidinm pasqualei, p. 71. 



Head with 3 to 14 circlets of hooks 21. 



21. Head M-ith 13 to 14 circlets of hooks, strobila 12 to 20 cm. long; 45 to 50 



small testes : cirrus pouch 250 to 260 fi long and crossing the longitudinal 

 excretory canals; vitellarium rouglily spherical and smaller than the 

 ovarian lobes ; 1 large egg, 52 to 53 fi in diameter, in each egg capsule. 



Dipylidium chyzeri, p. 68. 



Head with not over 6 rows of hooks ; 90 or more testes ; 2 or more eggs in 



each egg capsule 22. 



22. Head with 6 circlets of hooks; strobila 10 to 23.5 cm. long; 130 to 140 



testes, cirrus pouch extends to the longitudinal excretory canals ; the me- 

 dian ovarian lobes crescentic, the lateral spherical ; the vitellarium reni- 

 form and as large as an ovarian lobe ; capsules with 2 to 15 eggs and at 

 times extending lateral of the longitudinal excretory canals. 



Dipylidium sexeoronatum, p. 65. 

 Head with 3 to 5 circlets of hooks; cirrus pouch extends across the ex- 

 cretory canals i*egularly or occasionally; vitellarium smaller than the 

 ovarian lobes or smaller than the median lobes 23. 



23. Head with 5 circlets of hooks; strobila 5 to 11 cm. long; 90 to 100 large 



testes; cirrus pouch curved, convex posteriorly, and extending distinctly 

 across the longitudinal excretory canals; vitellarium smaller than the 

 ovarian lobes ; spindle-shaped receptaculum seminis present ; vagina opens 

 posterior of the cirrus pouch aperture; eggs 25 n in diameter. 



Dipylidium oerleyi, p. 63. 



