. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 153 there is a wide confluence of ventral abdominal and thoracic blood, including some passing through the sternal muscle chambers of the last pair of pereiopods. last pleurobranch posterior arthrobranch last bran abdomen. dorsal sinus ior arthrobranch intersegnnenta pleural sinus. vessel Fig. 55. Side view of right posterior gills; the epipodite and podobranch of the seventh thoracic segment have been displaced, and the course of the afferent branchial vessels is
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 153 there is a wide confluence of ventral abdominal and thoracic blood, including some passing through the sternal muscle chambers of the last pair of pereiopods. last pleurobranch posterior arthrobranch last bran abdomen. dorsal sinus ior arthrobranch intersegnnenta pleural sinus. vessel Fig. 55. Side view of right posterior gills; the epipodite and podobranch of the seventh thoracic segment have been displaced, and the course of the afferent branchial vessels is shown. From each infrabranchial sinus the deoxygenated blood proceeds into a series of 21 afferent branchial vessels (figs 44, 53, 55, 56) running along the outer part of the axes o^the serially-arranged gills in the second to the eighth thoracic segments. Each epipodite (fig. 55) is also furnished with a vessel which arises as a branch of the afferent branchial to the corresponding podobranch, and in serial sections of the puerulus stage it is also evident that an afferent vessel passes from the anterior end of the infrabranchial sinus into the epipodite of the first maxilliped. By serial sections of the gills and observations of injected specimens, it can be shown that offshoots from the afferent branchial vessel traverse the lateral mantle canals and, radiating into the gill filaments, convey deoxyge- nated blood into the outer afferent channels in the filaments (fig. 44). The wall of each filament functions as a respiratory membrane and, after oxygenation, the blood enters the efferent channel (fig. 44) which lies on the inner side of the filament and is separated from the afferent channel by a longitudinal connective-tissue septum. The actual transition from the afferent to the efferent channel is problematic. Bock (1925) concluded that in Astacus it could only be established through blood lacunae at the apex of the filament but, according to Dornesco & Homei (1940),
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
