. Fresh-water biology. Freshwater biology. PARASITIC FLATWORMS 423 243 (242) Cephalic glands open into ducts posterior to acetabuliim. . 244 244 (24s) Cephalic region crowned with spines; two eye-spots present. Cercaria gracillima Faust. Body length to mm., width to mm. Cephalic glands in posterior third of body. A pair of flame cells (in pockets) in posterior third of excretory trunks. Eye-spots lying directly lateral to cephalic ganglia, unpigmented. Genital rudiment extends anterior to acetabulum. Tail about twice body length, furcae of same length as undivided portion.
. Fresh-water biology. Freshwater biology. PARASITIC FLATWORMS 423 243 (242) Cephalic glands open into ducts posterior to acetabuliim. . 244 244 (24s) Cephalic region crowned with spines; two eye-spots present. Cercaria gracillima Faust. Body length to mm., width to mm. Cephalic glands in posterior third of body. A pair of flame cells (in pockets) in posterior third of excretory trunks. Eye-spots lying directly lateral to cephalic ganglia, unpigmented. Genital rudiment extends anterior to acetabulum. Tail about twice body length, furcae of same length as undivided portion. In long attenuated sporocysts in liver of Physa gyrina Say, near Buckhouse Bridge, Bitter Root River, Montana. 24s (244) Cephalic region crowned with two small tubercules; eye-spots lacking Cercaria tuberistoma Faust. Body length mm., width to mm. Tail about mm., furcae equal in length to undivided portion. Cephalic glands small; excretory system simple, most anterior tubules of tail reflexed, bladder muscular. In sporocysts, either dumbbell shaped or attached at one end. No birth pore. Cercariae escape by splitting wall of sporocysts. In Uver tissue of Physa gyrina Say, Bitter Root River, CorvaUis, Montana. 246 (241) Modification consists of lateral spines in rows. Setiferous cercariae. None yet recorded from North America. A small group, mostly marine. 247 (191) Tail apparently entirely wanting 248 The tail may be small and easily lost or actually not developed. 248 (249) Develop in rediae or tmbranched sporocysts. The young distomes possess no cyst or protective mem- brane. Found not infrequently in our fresh-water mussels. Species not described. Adults unknown. One of the Eiuro- pean species is thought to be the larva of Asymphylodora. Cercariaeum helicis (Leidy) 1847. Total length mm.; breadth mm., active and very extensive. Body white, oval, with oval tail. Oral sucker marked by radial lines; acetabulum central, equal in size to o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
