PARASITIC Fl.ATWOKMS 4^7 



armed with strong hooks. Female glands single, median; two vaginae. Eggs with ilirtc 

 membranes. 



The type species, D. laeyis, from various ducks and geese found in North .\mcrica .\o 

 record of any species on this continent. 



vt ov vi 



Fig. 757. Diplopostke laevis. Optical section of ripe proglottid; vd, vas deferens; /, testes; u, uterus 

 vt, vitellaria; ov, ovary; vs, seminal vesicle; v, vagina; X 22. (After Jacobi.) 



103 (61) Uterus with median stem and lateral branches; female genital 



glands in posterior end of proglottid. 



Family Taexiid.ve Ludwig 1886. 

 Splex usually with well-developed rostellum armed with double crown of hcxjks, rarely with 

 rudimentary unarmed rostellum. Suckers unarmed. Terminal segments longer than broad. 

 Reproductive organs single in each proglottid. Cicnital pores irregularly alternate. Vas 

 deferens coiled, seminal vesicle absent. Testes numerous, scattered. Double ovary poste- 

 rior, median, posterior to which is the yolk gland. Egg with thin outer membrane, and thick 

 brown radially striated inner shell. Adults in mammals and birds. 



Taenia Linnaeus 1758. 



Forms rightly included here are as adults characteristic parasites of higher carnivorous land 

 animals and the larval forms (cysticerci) also occur in land-living herbivorous or omnivorous 

 mammals. 



Eggs are distributed widely by surface waters. Larval stages occur rarely in aquatic mam- 

 mals, e.g., Cysticcrcus fasciolaris the bladder-worm of Taenia crassico/lis of the cat wliich Stiles 

 and Hassall, and later Linton also, have reported from the muskrat. 



104 (60) Female genital pore not adjacent to cirrus and male pore. . . 105 



105 (112) Proglottids without lateral appendages. Female genital {xjre is 



entirely lacking. 



Family Acoleidae Fuhrmann 1007 . . 106 

 Thick-bodied cestodes with rostellum usually armed. Proglottids short. Musc-ulature 

 very powerful. Cirrus sac very large; cirrus armed with strong spines. Eggs with 3 mem- 

 branes. In birds. 



106(111) Hermaphroditic forms 107 



107(110) ]\Iale and female genital organs simple 108 



108 (109) Testes numerous; seminal receptacle very large; uterus a trans- 



verse tube anterior to ovary. Male genital pores regularly 



alternate icolcus Fuhrmann 1809. 



Scolex small with armed rostellum. Reproductive organs single. Cirrus-pouch passes 

 ventral of longitudinal excretory vessels and nerve. V'^agina closed, functions as very large 

 seminal receptacle. Adults in water birds. 



Type species lr()/(7/.s (/rmc;///.? Fuhrmann 1899. 



From the black-necked stilt; parasite not reported from North .\merica. 



109 (108) Testes few; seminal receptacle very small; uterus encircling 



ovary; male pores irregularly ahernate. 



Ciyrococlia Fuhrmann iSoo. 

 Rostellum armed with single crown of hooks arranged in zig-zag row having eight angles. 

 Reproductive organs single in each proglottid. Cirrus |>nuh jKisses In-tween longitvidina! 

 excretory vessels and dorsal of nerve. Cterus ring-like, with numerous outixHketings. and 

 with opening in terminal proglottids both dorsally and ventrally in median line of posterior 

 margin. Adults in birds. 



In water birds; not reported in North .Vmerica. 



