. Fresh-water biology. Freshwater biology. 442 75 (76) FRESH-WATER BIOLOGY Strobila broad, lancet-shaped. Ovary and vitellarium ante-poral, alongside of testes. Drepanidotaenia Railliet 1892. Scolex very small, with 8 hooks. Neck wanting. No accessory sac in genital atrium. Type species. . Drepanidotaenia lanceolata (Bloch) 1782. Adult in intestine of ducks and geese; cosmopolitan. Bladder-worm in various Cyclopidae and Diaptomus. Fig. 746. Drepanidotaenia lanceolata. Transverse section of proglottid; «, uterus; ut, vitellaria; ov, ovary; /, testes; id, vas deferens; sr, seminal receptacle; v,
. Fresh-water biology. Freshwater biology. 442 75 (76) FRESH-WATER BIOLOGY Strobila broad, lancet-shaped. Ovary and vitellarium ante-poral, alongside of testes. Drepanidotaenia Railliet 1892. Scolex very small, with 8 hooks. Neck wanting. No accessory sac in genital atrium. Type species. . Drepanidotaenia lanceolata (Bloch) 1782. Adult in intestine of ducks and geese; cosmopolitan. Bladder-worm in various Cyclopidae and Diaptomus. Fig. 746. Drepanidotaenia lanceolata. Transverse section of proglottid; «, uterus; ut, vitellaria; ov, ovary; /, testes; id, vas deferens; sr, seminal receptacle; v, vagina; magnified. (After Wolffhugel.) 76 (75) Strobila slender or even filiform. Ovary and viteUaritim ventral to testes or between them. 77 77 (78) Suckers entirely unarmed, or at most armed with hooks on margin only. Hymenolepis Weinland 1858. Rostellum well developed, rarely rudimentary or absent. Accessory sac generally wanting in genital atrium. Rarely as abnormality 2, 4, 5, or 6 testes in a single proglottid. CMeiiy in land and water birds; some species in mam- mals. A very large genus; about 50 species occur in aquatic hosts found in North America. Among them a few are definitely reported for North America. H. compressa (Linton) 1892 from the scoter and canvas-back. H. fusus in which Fuhrmann places Linton's Taenia filum from gulls at Yellowstone Lake. H. megaiops described by Ransom (with other species from land birds) from the pintail duck; Missouri River, Fig. 747. Hymenolepis megaiops. Dorsal view of mature segment (no. 172). Reconstruction from sections; br, retractor of cirrus-pouch; ci, cirrus; cr, retractor of cirrus; dc, dorsal excretory canal; gc, genital cloaca; nt, main lateral nerve; sg. shell gland; t, testis; tm, transverse muscles; ut. uterus; DC, ventral excretory canal; vg, vagina; vs, seminal vesicle; vs', seminal vesicle of cirrus-pouch; xpl, plexusof excretory vessels; y^, yolk glands. X 90. (After Ransom.) 78 (77) Suckers armed on borders a
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
