. Fresh-water biology. Freshwater biology. 734 FRESH-WATER BIOLOGY 228 (226, 227) With one tooth on labium; no spine on valves. Chydorus poppei Richard Like hyhridus but without spine at infero-posteal angle. Tooth on labium sometimes small or obso- lescent. Louisiana, Cahfornia; rare. Very probably the last two spedes should be listed as varieties of barroisi. These species were first placed in Pleuroxus, but have no very close affinity with either Pleuroxus or Chydorus; might well be made a separate genus. Fig. 11S7. Chydorus poppei. MM. 229 (211) Post-abdomen large, pre-anal angl
. Fresh-water biology. Freshwater biology. 734 FRESH-WATER BIOLOGY 228 (226, 227) With one tooth on labium; no spine on valves. Chydorus poppei Richard Like hyhridus but without spine at infero-posteal angle. Tooth on labium sometimes small or obso- lescent. Louisiana, Cahfornia; rare. Very probably the last two spedes should be listed as varieties of barroisi. These species were first placed in Pleuroxus, but have no very close affinity with either Pleuroxus or Chydorus; might well be made a separate genus. Fig. 11S7. Chydorus poppei. MM. 229 (211) Post-abdomen large, pre-anal angle ordinarily not prominent. Alonella Sars 1862 . 230 This genus consists of a heterogeneous assemblage of forms; not assignable elsewhere and not easily separable. There are 3 sections which might well constitute separate genera: (i) Alonella proper. Rostrum long, slender, recurved; usually conspicuously so; post- abdomen with marginal denticles only; claws with i basal spine. A. roslrala, dadayi, nana. (2) Paralonella. Rostrum short, hardly exceeding antennules; post-abdomen with very small marginal denticles, with or without lateral fascicles; claws with i basal spine. A. karua, denttfera, diaphana, globulosa. (3) Pleuroxalonella. Rostrum moderate; post- abdomen with marginal denticles only; claws with 2 basal spines. Pleuroxus-]ike. A. excisa, exigua. 230 (23 s) Rostrum short; post-abdomen with marginal and lateral denticles. 231 231 (234) Valves with infero-posteal angle toothed 232 232 (233) About 3 fine teeth; valves striated. Alonella karua (King) 1853. General shape like Alona and eaaly taken for a member of that genus. (See 132.) Valves with oblique striae; infero- posteal angle with 1-4 minute teeth. Post-abdomen broad, expanded behind anus; apex rounded; with about 8 minute marginal denticles and as many lateral fascicles, much larger. Claws with i small basal spine. Color yellow, trans- parent. Length, J,; $ (South America), mm. Louisiana, Texas, Arkansas
Size: 1709px × 1461px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
