Text-book of comparative anatomy . niscidce the outer lamellce CRUSTACEA—GILLS 323 of the anterior pleopoda contain air chambers. In the Anisojmla the pleopoda an-birumusc swimming feet, not serving for respiration. Thoracostraca.—In the Stomatopoda we find on the strong abdomen 6 pairs ofwell-developed typical biramose pleopoda. The 5 anterior pairs are swimming feet,eacli of whose outer lamella? carries a branched gill. The 6th pair of pleopoda formwith the telson (7th abdominal segment) a strong caudal fin. In the Cumacea the 6th pair of pleopoda (A, _??6) consists of long bifurcatedprocess
Text-book of comparative anatomy . niscidce the outer lamellce CRUSTACEA—GILLS 323 of the anterior pleopoda contain air chambers. In the Anisojmla the pleopoda an-birumusc swimming feet, not serving for respiration. Thoracostraca.—In the Stomatopoda we find on the strong abdomen 6 pairs ofwell-developed typical biramose pleopoda. The 5 anterior pairs are swimming feet,eacli of whose outer lamella? carries a branched gill. The 6th pair of pleopoda formwith the telson (7th abdominal segment) a strong caudal fin. In the Cumacea the 6th pair of pleopoda (A, _??6) consists of long bifurcatedprocesses. The pleopoda of the 5 anterior abdominal segments are wanting in thefemale ; in the male they are swimming feet (H], and either present in their fullnumbers or in 2 to 3 pairs. In the Schizopoda the 6th pair of pleopoda (C) forms with the telson a caudal there is an auditory organ it lies on the inner lamella of this pleopod. The5 anterior pairs of pleopoda are well-developed biramose swimming feet, in the male D. FIG. 224.—Thoracic feet of Astacus fluviatilis (after Huxley). .4, 2d thoracic foot (2d maxil-lipede). B, 1st thoracic foot (1st maxillipede). C, Part of transverse section through the thorax,showing an ambulatory foot and gills. D, 3d thoracic foot (3d maxillipede). /, II, Joints ofthe protopodite ; 1-5, of the endopodite en ; ex, exopodite ; pob, podobranchire ; «&, arthrobranchia?;plb, pleurobrauchife ; k, masticatory ridge. at least. The 2 anterior pairs serve as copulatory organs in the Euphausidce. Inthe male of Siriella the pleopoda carry gills (£). Dccapoda (1-N}.—The development of the pleopoda stands in direct relation tothe development of the abdomen itself. In the long-tailed Dccapoda (Macrura) 6pairs of biramose pleopoda are generally found. The 6th pair with the telson formsa strong caudal fin. The 5 anterior pairs play no very important part in the Bracliyura the pleopoda, in correspondence with the great reduction
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
