. Fresh-water biology. Freshwater biology. 736 FRESH-WATER BIOLOGY 237 (236) Denticles of ordinary size; infero-posteal tooth present. 238 238 (243) Claws with one basal spine 239 239 (242) Rostrum long, recurved 240 240 (241) Shape elongated oval; valves striated. Alonella rostrata (Koch) 1841. General form not unlike a Pleuroxus of the slrialus type. Valves striated or reticulated; infero-posteal angle rounded and with minute tooth, sometimes ab- sent. Rostrum long, slender, recurved. Post-ab- domen moderately long, somewhat tapering toward apex; angle rounded; 9-12 small marginal denticles.
. Fresh-water biology. Freshwater biology. 736 FRESH-WATER BIOLOGY 237 (236) Denticles of ordinary size; infero-posteal tooth present. 238 238 (243) Claws with one basal spine 239 239 (242) Rostrum long, recurved 240 240 (241) Shape elongated oval; valves striated. Alonella rostrata (Koch) 1841. General form not unlike a Pleuroxus of the slrialus type. Valves striated or reticulated; infero-posteal angle rounded and with minute tooth, sometimes ab- sent. Rostrum long, slender, recurved. Post-ab- domen moderately long, somewhat tapering toward apex; angle rounded; 9-12 small marginal denticles. Claws with i minute basal spine. Color yellow or brown, usually rather dark. Length, 9, ca. mm.; $, ca. mm. Rather rare; reported from New England, Michi- gan, Wisconsin, Minnesota; probably to be found in all regions. This species is Pleuroxus acutirostris Fig. H62. Alonella rostrata. 241 (240) Shape short oval; valves strongly reticulated. Alonella dadayi Birge 1910. Shape oval-rotund. Valves strongly reticulated all over; infero-posteal angle rounded, with sev- eral minute teeth. Rostrum long, pointed, re- curved. Keel of labrum acuminate behind and its margin with i projection. Post-abdomen short, wide; pre-anal angle strongly marked, as in Chydorus; with numerous small denticles; apex rounded. Claws with i basal spine. Color yellow to brown, often opaque. Length, 9> mm.; $ (South America), mm. Louisiana, Texas; not rare in weedy pools. This species is Leptorhynchus dentifer Daday, whose specific name has to be changed on remov- ing to ilfo«e//s, as Sars' species A. dentifera pre- occupies the name. Fig. 1163. Alonella 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
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
