. Fresh-water biology. Freshwater biology. 376 FRESH-WATER BIOLOGY 13(27) Posterior disc with six suckers 14 14 (26) Posterior disc terminal; suckers large. Poly stoma Zeder 1800 IS Six suckers in a circle or in two rows somewhat separated in the median line. In the center of each sucker a small hook, and others on anterior and posterior margins of shield; between posterior acetabula twi) large hooks. Vagina double, one pore on each side near the ante- rior end. Eggs without polar filament. Genital atrium with circle of hooks. Several species in reptiles and amphibians. Not common but widely d
. Fresh-water biology. Freshwater biology. 376 FRESH-WATER BIOLOGY 13(27) Posterior disc with six suckers 14 14 (26) Posterior disc terminal; suckers large. Poly stoma Zeder 1800 IS Six suckers in a circle or in two rows somewhat separated in the median line. In the center of each sucker a small hook, and others on anterior and posterior margins of shield; between posterior acetabula twi) large hooks. Vagina double, one pore on each side near the ante- rior end. Eggs without polar filament. Genital atrium with circle of hooks. Several species in reptiles and amphibians. Not common but widely distributed. P. integerrimum Zeder, type of the genus, is not reported from North America. American species worked out by Stunkard. All North American forms fall in the section of the genus characterized by the presence of a short uterus containing a single egg; to these forms a new subgeneric name should be given. Polystoma {Polystomoides) Ward. IS (23) Great hooks present on caudal disc and well developed. 16 16 (22) Genital hooks of equal length 17 17 (18, 21) Not more than 16 genital hooks. P. {Polystomoides) hassaili Goto 1899. Length to 2 mm.; width to mm. Caudal suckers to mm. in diameter. Caudal disc with 18 hooks, the largest mm. and the smallest mm. long. Cir- rus hooks mm. long with a winglike process at the middle. Uterus contains only a single large egg measuring by nun. to by 34 nun. Urinary bladder of Cinosternum pennsylvan' icum, Aromochelys carinatus, A. odoraius, Chd- X18. yi''"' serpentina; Maryland, North CaroUna, Texas, Iowa,. Fio. 653. Polystoma hassaili. Ventral view. (After Stunkard.) 18 (17, 21) Genital hooks 32 ig 19 (20) Acetabula large, adjacent, not contiguous; pharynx smaller than oral sucker. . P. (Polystomoides) coronatum Leidy 1888. Body by mm. Caudal suckers mm. in diameter. Caudal disc with one pair of great hooks, mm. long, one pair of intermediate hooks, m
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
