. Fresh-water biology. Freshwater biology. 732 219 (2i8) FRESH-WATER BIOLOGY Dorsal surface not flattened; form usually spherical or broadly ovate. . 220 220 (223, 224) Small forms not exceeding mm., usually less. . 221 221 (222) Fornices gradually narrowing into rostrum. All olfactory setae on end of antennule. Chydorus sphaericus (0. F. Mtiller) 1785. Spherical or broadly elliptical. Shell usually reticulated, sometimes smooth (var. nitidus Schoedler), sometimes punctate (var. pundatuslltlWch), or with elevations (var. coelalus Schoedler). Post-abdomen with 8-g marginal denticles. Claws
. Fresh-water biology. Freshwater biology. 732 219 (2i8) FRESH-WATER BIOLOGY Dorsal surface not flattened; form usually spherical or broadly ovate. . 220 220 (223, 224) Small forms not exceeding mm., usually less. . 221 221 (222) Fornices gradually narrowing into rostrum. All olfactory setae on end of antennule. Chydorus sphaericus (0. F. Mtiller) 1785. Spherical or broadly elliptical. Shell usually reticulated, sometimes smooth (var. nitidus Schoedler), sometimes punctate (var. pundatuslltlWch), or with elevations (var. coelalus Schoedler). Post-abdomen with 8-g marginal denticles. Claws small; proximal basal spine very minute. $ with post-abdomen much emarginate. Color light yellow to dark brown. Length, 9>°-3~o-S mm.; $, mm. Small limnetic forms constitute var. minor Lilljeborg. The commonest of all Cladocera; found all over the Fig, 1151. Chydorus sphaericus. 222 (221) Fornices abruptly narrowed into rostrum. Two olfactory setae on side of antennule. . Chydorus piger Sars 1862. General form much like C. sphaericus. Ventral margin of valves densely ciliated; valves ordinarily marked by oblique striae, sometimes smooth. Fornices abruptly narrowed at rostrum. Antennule with usual lateral sense seta and two olfactory setae on side. Post-abdomen with 8-9 rather long marginal denticles. Claws with 2 basal spines, the proximal one minute. J post-abdomen narrow, but not excavated. Color light to dark yellow. Length, 9 > '^- °'4 mm. Rare; reported only from Maine. i-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ward, Henry Baldwin, 1865-1945; Whipple, George Chandler, 1866-1924. joint author. New York, John Wiley & sons, inc. ; [etc. ,etc. ]
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
