Text-book of comparative anatomy . 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 of theabdomen, are reduced. A caudal fin is usually wanting. In the male only the 2anterior pairs of pleopoda are found, in the female 4 pairs. The caudal fin isgenerally reduced in the Anomura, and the pleopoda are truncated and onlydeveloped on one side. The 2 an
Text-book of comparative anatomy . 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 of theabdomen, are reduced. A caudal fin is usually wanting. In the male only the 2anterior pairs of pleopoda are found, in the female 4 pairs. The caudal fin isgenerally reduced in the Anomura, and the pleopoda are truncated and onlydeveloped on one side. The 2 anterior pairs of pleopoda very generally serve inthe Dccapodan male as copulatory organs. In the female the pleopoda often carrythe eggs after their discharge and fertilisation. 324 COMPARATIVE ANATOMY CHAP. C. The Respiratory Organs—Gills. Respiration always takes place in Crustaceans by means of theouter integument. In small Crustaceans, in which the cuticle lyingover the hypodermis is thin and delicate, the whole body surface. FIG. 225.—Pleopoda (abdominal feet) of Leptostraca and Malacostraca. A, End of theabdomen of Diastylis stygia (after G. O. Sars); V, VI, VII, abdominal segments ; VII, telson ; p6,pleopoda of the 6th segment; en, eudopodite ; ex, exopodite. Ji, 2d pleopod with gills, exo- andeudo-podite of Siriella Thompson!! (after G. O. Sars). C, End of the abdomen (caudal fin) of Siri-ella gracilis (after G. O. Sars); VI, 6th abdominal segment; VII, 7th abdominal segment (telson);CH, ex, endo- and exo-podites of the 6th pleopoda, which together with the telson form the caudalfin ; (/, auditory organ. D, An anterior pleopod of Nebalia (after Glaus); ex, exopodite; en,endopodite. E, Nebalia, 6th pleopod of the 9 (after Glaus). F, Anilocra (/sopod), caudal tin ; VI,6th abdominal segment; VII, telson ; p6, 6th pleopod with exopodite (ex) and endopodite (en) (afterDelage). JPi Vi fA VH) abdo
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
