. Bulletin. Science. T^NIOID CESTODES OF NOETH AMERICAN BIRDS. 17 tions of the segment within the inner field. As in Davainea rhyn- chota^ on the ri^ht-hand side this mass extends nearly to the anterior border of the segment; on the left-hand (pore) side it is limited to the posterior two-thirds. The vas deferens (fig. 7, v. def.) forms a mass of coils in the anterior third of the segment extending from the median line to the base of the cirrus pouch. The cirrus pouch (figs. 7, 8, c. p.) is pyriform in shape, with thin outer muscular wall, as in Davainea rhynchota. It is, however, somewhat sma
. Bulletin. Science. T^NIOID CESTODES OF NOETH AMERICAN BIRDS. 17 tions of the segment within the inner field. As in Davainea rhyn- chota^ on the ri^ht-hand side this mass extends nearly to the anterior border of the segment; on the left-hand (pore) side it is limited to the posterior two-thirds. The vas deferens (fig. 7, v. def.) forms a mass of coils in the anterior third of the segment extending from the median line to the base of the cirrus pouch. The cirrus pouch (figs. 7, 8, c. p.) is pyriform in shape, with thin outer muscular wall, as in Davainea rhynchota. It is, however, somewhat smaller in the present species, measuring 90 to 100/x in length by 45 to 50/^ in diameter in its widest portion. The arrangement in the pouch of the vas def- erens and cirrus is similar to that in the other species. The cirrus is without apparent spines, and measures in the retracted condition about 50/x, in length by 2 to 4/x in diameter. cap.^. Pig. 8.—Davainea comitata: Geavid segment, ventral view, Egg capsules. c. p., CiKEtJS POUCH, vag., Vagina. Female organs.—The vaginal opening is immediately posterior of the male opening. The vagina and seminal receptacle are in this form similar to those of Davainea rhynchota^ with the exception that the vagina for a distance of 25/* from the genital pore is constricted, and this constricted portion is surrounded by a bulbous sphincter. The ovary (fig. 7, o^y.), located as in Davainea rhynchota., is similar in shape, lobulation, etc., and measures about 200/i in width at its maximum of development. Posterior and ventral of the ovary is the yolk gland (fig. 7, y. g.) 100 to 130/x in diameter, and dorsal and anterior of the latter is the small shell gland, 50/x in diameter. In the gravid segment the eggs are grouped 6 to 12 together m Qgg capsules (fig. 8, cap.)., measuring 80 to 90/^ in diameter. From 40 to 50 capsules are visible from a surface view of the segment. They are confined to the medullary portion of the segment insid
Size: 2202px × 1135px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorun, bookcentury1900, bookdecade1900, booksubjectscience
