. Fresh-water biology. Freshwater biology. THE FAIRY SHRIMPS (PHYLLOPODA) 663 small and often unsegmented. The second antennae are vestigial or absent in the Notostraca; in the male anostracans they form variously modified clasping organs; and in the Conchostraca they are biramous swimming appendages. Male Anostraca often bear frontal organs which may arise from the bases of the second anten- nae or from the front of the head. The trunk-Hmbs are leaf-hke in form (hence the name Phyllopoda) and are remarkable for hav- ing gnathobases, or "chewing bases," far removed from the mouth. Th
. Fresh-water biology. Freshwater biology. THE FAIRY SHRIMPS (PHYLLOPODA) 663 small and often unsegmented. The second antennae are vestigial or absent in the Notostraca; in the male anostracans they form variously modified clasping organs; and in the Conchostraca they are biramous swimming appendages. Male Anostraca often bear frontal organs which may arise from the bases of the second anten- nae or from the front of the head. The trunk-Hmbs are leaf-hke in form (hence the name Phyllopoda) and are remarkable for hav- ing gnathobases, or "chewing bases," far removed from the mouth. The first or the first and second pair are modified in male Con- chostraca for clasping the female. In female Notostraca the limbs of the eleventh trunk somite are modified to form brood-pouches, or "oostegopods," for carrjdng eggs. The females of some Conchostraca have the flabella of two or three limbs near the genital aperture enlarged and the egg masses are attached to these. In the Anostraca the appendages of the somites on either side of the genital opening are modified for reproduction in both sexes. In addition to the various appendages which serve as accessory reproductive organs, the oviducts unite to form an external uterine chamber in the Anos- traca, and the males of the same suborder have a copulatory organ formed by the fusion of the extremities of the vasa deferentia. All phyllopods are of separate sexes. Males are much less common than females, in fact some species are known only from female specimens, and the development of several is believed to be usu- ally parthenogenetic. The gonads are paired and have a simple tubular structure, except in the Notostraca where they are much ramified. In the Anostraca the eggs are carried in the female's brood-pouch, the uterine portion of the oviduct, sometimes until they hatch. The Notostraca bear the eggs in the special receptacles formed by the eleventh pair of trunk-limbs, and the Conchostraca carry them enclos
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
