. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 136 ANNALS OF THE SOUTH AFRICAN MUSEUM epi meral attractor muscle cardiac region of carapace ^ ,, ateral parts of lateral \\\\, thoraco-abdomi nal muscle. obi I que muscles- -triangular sclerite Fig. 45. Diagrammatic inner view of muscles associated with the pericardial pouches. membrane, and some may even originate in the postero-dorsal corner of the branchial chamber. They curve medially and are then usually inflected pos- teriorly to converge on a narrow, slightly thickened insertion on the line o
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 136 ANNALS OF THE SOUTH AFRICAN MUSEUM epi meral attractor muscle cardiac region of carapace ^ ,, ateral parts of lateral \\\\, thoraco-abdomi nal muscle. obi I que muscles- -triangular sclerite Fig. 45. Diagrammatic inner view of muscles associated with the pericardial pouches. membrane, and some may even originate in the postero-dorsal corner of the branchial chamber. They curve medially and are then usually inflected pos- teriorly to converge on a narrow, slightly thickened insertion on the line of flexure of the intertergal membrane. Associated with the longitudinal fibres, and probably also with some very delicate fibres in the posterior half of the intertergal membrane, are tvvo parallel bundles of oblique fibres (fig. 45). These arise on the epimeron behind the epimeral attractor muscle and below the lateral portions of the lateral thoraco-abdominal muscle. Passing in a postero-medial direction under the medial section of the latter muscle, they are inserted at the base of the longitudinal muscles. They are probably con- cerned with the infolding of the membrane, ^vhile the transverse and longi- tudinal fibres may be responsible for alternate constriction and shortening of the intertergal membrane and the pouches. Pei"icardial pouches have been reported in a number of decapod Crus- tacea, but for many years their function has been uncertain. In 1939, however, Drach drew attention to the fact that, although the new lining of the gut in marine Brachyura is responsible for water absorption, the pericardial pouches act as storage organs for the absorbed water, and the elasticity of their walls is eflfective in controlling the hydrostatic pressure within the body during the critical period of ecdysis. Bliss (1956, 1963) has also proved experimentally that in the land crab, Gecarcinus lateralis, while they may be the normal focus of intake and retention of Avater dur
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
