. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 99 adductor basipod reductor exop adductor exopod abductor exopodi flcgellans exopoditis. ol rotator or basipod. r exopod. Fig. 28. Ventral view of muscles of left third pleopod of male. Remotor Backward movement of the pleopod is effected by this muscle, which differs in the two sexes, being slender in the male but comparatively wide and composed of three bundles in the female appendage. In both sexes it is ventral to the promotor muscle, and is attached antero-l
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE ANATOMY OF THE CAPE ROCK LOBSTER 99 adductor basipod reductor exop adductor exopod abductor exopodi flcgellans exopoditis. ol rotator or basipod. r exopod. Fig. 28. Ventral view of muscles of left third pleopod of male. Remotor Backward movement of the pleopod is effected by this muscle, which differs in the two sexes, being slender in the male but comparatively wide and composed of three bundles in the female appendage. In both sexes it is ventral to the promotor muscle, and is attached antero-laterally on the pleuron and inserted ventrally by a short tendon on the proximal border of the coxopodite. Dorsal rotator This is a thick band, divisible into upper and lower bundles which ori- ginate postero-laterally on the tergum behind the promotor muscle. It slants obliquely inward dorsal to the remotor muscle and, traversing the coxopodite, is inserted ventrally on the middle of the proximal border of the basipodite by a conspicuous, fiat tendon. It is comparable to the musculus rotator dorsalis basipoditis of Astacus and Pandalus, but differs in having a ventral and not a dorsal insertion. Ventral rotator Arising at the anterior junction of the sternum and pleuron, this muscle tapers rapidly towards its medial insertion by a slender tendon on the proximal edge of the basipodite. In the male pleopod it is feebly developed and consists of only a few fibres, but in the female there is an additional, more substantial bundle that practically obscures the weaker element ventrally. The two rotator muscles probably correspond to the levator and depressor muscles of the thoracic appendages, and are functionally antagonistic, the dorsal one turning the appendage outward and forward and the ventral one pulling it inward and forward. Abductor basipoditis Some specific variation is apparent in the number of remaining muscles associated with the basipodite. In Astacus there is a singl
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
