. Fresh-water biology. Freshwater biology. 4i6 FRESH-WATER BIOLOGY 198 (197) Tail long with terminal organ for attachment. Megalurous cercariae. Single American species known. Cercaria megalura Cort 1914. Develops in rediae. Cystogenous glands abundant. Does not swim in open water or use tail as swimming organ, but as a stalk, becoming attached by the adhesive organ, a group of unicellular glands at the tip. The tail has the power of elongating very greatly. In this position the worm waves or wriggles about in a serpentine fashion. When taken up in a pi- pette it encysts quickly and this seems
. Fresh-water biology. Freshwater biology. 4i6 FRESH-WATER BIOLOGY 198 (197) Tail long with terminal organ for attachment. Megalurous cercariae. Single American species known. Cercaria megalura Cort 1914. Develops in rediae. Cystogenous glands abundant. Does not swim in open water or use tail as swimming organ, but as a stalk, becoming attached by the adhesive organ, a group of unicellular glands at the tip. The tail has the power of elongating very greatly. In this position the worm waves or wriggles about in a serpentine fashion. When taken up in a pi- pette it encysts quickly and this seems to be normal on contact with fresh water. From Fleurocera elevatum, Sangamon River, 111., and Goniobasis mrginica, Princeton, N. J. Adult unknown. Reproductive organs indicated by two masses of nuclei joined by line. 199 (195) One or more spines present at anterior end. 200 200 (224) Anterior end provided with single median boring spine. Stylet cercariae 201 These forms called Acanthocephala by Diesing and Xiphidiocercariae by Liihe are numer- ous and perhaps not closely related; even if the stylet cercariae do belong to different adults, their assemblage in a single group is convenient. Small, slender-tailed cercariae with rounded anterior margin, bearing a dagger-shaped boring spine or stylet, usually in the upper Hp of the oral sucker. The form of this organ is very definite in each species and varies between different species chstinctly enough to form in many cases a valuable mark for diagnosis. Eye spots are usually wanting. Development in sporocysts is most frequent and encystment in a second intermediate host usual in species of which the development is known. 201 (217) Tail slender, not provided with special organs (bristles, fin-fold) or regions. . 202 202 (203) Stylet glands few in number, not more than four on each side. Tail attached to median posterior extremity, not arising from distinct caudal pocket. Cercariae microcotylae. Very small. Body less than mm. lo
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
