. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 55 membrane behind. Although weakly developed, they doubtless assist in move- ments of the intersegmental arthrodial membranes during extension and flexion of the abdomen. deeper extensors 1 Superficial extenso dorsal arth I ate ra\ a bdo Superficial extensor deeper extensor deeper extensor 4. Superficiol dorsal thoroco-abdomi ncl lateral thoraco-abdominal entrol 2 etc. X i I I a ry 1 ateral obdominal 2 promoter of pleopod 1 ateral abdominal 3 anterior obiique ux
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 55 membrane behind. Although weakly developed, they doubtless assist in move- ments of the intersegmental arthrodial membranes during extension and flexion of the abdomen. deeper extensors 1 Superficial extenso dorsal arth I ate ra\ a bdo Superficial extensor deeper extensor deeper extensor 4. Superficiol dorsal thoroco-abdomi ncl lateral thoraco-abdominal entrol 2 etc. X i I I a ry 1 ateral obdominal 2 promoter of pleopod 1 ateral abdominal 3 anterior obiique ux c I lary 3 central 4 S. 5 etc. Fig. 12. Dorsal view of anterior part of abdomen, showing the dorsal musculature. In their investigation of the thoraco-abdominal junction of Procambarus, Pilgrim & Wiersma (1963) have described certain other dorsal and lateral membrane muscles, but these appear to be similar to the muscles herein interpreted as intrinsic muscles of the pericardial pouches (p. 135-6). Superficial extensors (Figs 8, 10, 12, 31, 54) Mid-dorsally below the terga of the first five abdominal segments there are paired, strap-shaped muscles, each of which consists of medial and lateral bundles of almost straight fibres. Although they are uniformly arranged, they are not directly continuous, for each muscle originates near the anterior edge of the tergum and is inserted posteriorly on the next intertergal membrane, so that there is a slight gap between the insertion of one muscle and the attach- ment of the next one behind. As in Procambarus (Pilgrim & Wiersma, 1963), in most segments the lateral division is attached on an oblique tergal ridge postero-lateral to the level of the attachment of the medial portion. The superficial extensors of the first abdominal segment arise immediately behind the insertions of the superficial dorsal thoraco-abdominal muscles, but the two of the pair are more widely separated than usual and do not adjoin in. Please note that these
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